P2002 Diesel Particulate Filter (DPF) Efficiency Below Threshold (Bank 1)

P2002 Diesel Particulate Filter (DPF) Efficiency Below Threshold (Bank 1) is a generic OBD-II diagnostic trouble code indicating that the Engine Control Module (ECM/PCM) has determined that the Diesel Particulate Filter (DPF) on Bank 1 is not operating with the expected particulate filtration efficiency.

The Diesel Particulate Filter is designed to capture soot and other particulate matter produced by a diesel engine before the exhaust gases leave the vehicle.

The ECM/PCM monitors the DPF using information from sensors and calculated operating parameters. Depending on the vehicle, this may include DPF differential pressure, exhaust gas temperature, exhaust flow, regeneration history, calculated soot loading, and other exhaust-system information.

When the ECM/PCM determines that the Bank 1 DPF efficiency has fallen below the manufacturer's programmed threshold, it may store P2002 and illuminate the Check Engine Light.

In simple terms, P2002 means the vehicle's computer believes the Bank 1 DPF is not filtering diesel particulate matter as effectively as expected.

However, P2002 does not automatically mean that the DPF is clogged or that the DPF must be replaced.

Possible causes include:

• Damaged or cracked DPF substrate

• Melted DPF substrate

• Excessive soot accumulation

• Excessive ash accumulation

• Failed or incomplete regeneration

• Exhaust leaks

• Faulty DPF differential-pressure sensor

• Blocked or damaged pressure-sensor hoses

• Faulty exhaust gas temperature sensor

• Damaged sensor wiring

• Fuel injector problems

• EGR system problems

• Turbocharger or boost problems

• Excessive soot production

• Incorrect engine oil

• ECM/PCM software or calibration problems

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What Does P2002 Mean?

The code contains several important terms.

Diesel Particulate Filter (DPF)

A Diesel Particulate Filter is an exhaust after-treatment component designed to trap particulate matter from diesel exhaust.

The filter contains a porous substrate that captures soot particles while allowing exhaust gases to pass through.

As soot accumulates, the DPF must periodically perform a process called regeneration.

During regeneration, exhaust temperature is raised sufficiently to oxidize accumulated soot.

A simplified process is:

Soot accumulation → regeneration → soot oxidation → reduced soot loading

Regeneration removes accumulated soot, but it does not remove all material from the filter.

Ash produced primarily from engine oil additives and other sources remains in the DPF and gradually accumulates.

This is why an older DPF can eventually require professional cleaning or replacement.

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Efficiency Below Threshold

“Efficiency below threshold” means that the ECM/PCM has determined that the DPF is not meeting its expected particulate filtration performance.

This is important because efficiency is not exactly the same thing as restriction.

A DPF can be heavily restricted by soot or ash.

But a DPF can also have poor filtration efficiency because its internal substrate is:

• Cracked

• Melted

• Broken

• Damaged

• Degraded

In such a situation, particulate matter may pass through the filter even though the filter is not necessarily producing the extremely high differential pressure associated with a severely blocked DPF.

Therefore, P2002 should not automatically be interpreted as “DPF clogged.”

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Bank 1

Bank 1 refers to the cylinder bank containing cylinder number one.

On a V-type diesel engine:

• Bank 1 = cylinder number one side

• Bank 2 = opposite side

Therefore:

P2002 = DPF Efficiency Below Threshold (Bank 1)

The corresponding Bank 2 code is:

P2003 = Diesel Particulate Filter Efficiency Below Threshold (Bank 2)

Inline diesel engines normally have only one cylinder bank, although exact diagnostic terminology depends on the engine and manufacturer.

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How Does a DPF Work?

A simplified diesel exhaust system can be represented as:

Diesel engine → DPF → downstream exhaust after-treatment → exhaust outlet

The exact configuration varies by vehicle.

The DPF captures soot produced during combustion.

As soot accumulates inside the filter, exhaust flow becomes increasingly restricted.

The engine control system therefore monitors DPF loading and initiates regeneration when necessary.

During regeneration, the exhaust temperature is increased so that accumulated soot can be oxidized.

A simplified representation is:

Normal operation → soot accumulation → regeneration → soot reduction

However, regeneration cannot remove accumulated ash in the same way it removes soot.

Over time:

Ash accumulation → reduced available filter volume → increased restriction and reduced service life

A DPF that has reached the end of its service life may therefore require professional cleaning or replacement.

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Why Would the ECM Set P2002?

The ECM/PCM uses multiple parameters to determine whether the DPF is functioning correctly.

Depending on the vehicle, it may monitor:

• Differential pressure across the DPF

• Exhaust gas temperature

• Exhaust flow

• Engine load

• Fuel injection

• Regeneration operation

• Soot-load calculations

• Ash-load calculations

• Oxygen or air-fuel sensor information

• Upstream and downstream exhaust conditions

If the measured or calculated DPF performance falls below the programmed threshold, P2002 may be stored.

The exact monitoring strategy is manufacturer- and engine-specific.

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Symptoms of P2002

The symptoms vary depending on the cause and severity of the DPF problem.

Check Engine Light

The Check Engine Light is the most common symptom.

In some cases, the vehicle may initially drive normally.

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DPF Warning Light

Some vehicles may also display a dedicated DPF or exhaust after-treatment warning.

Possible warnings include:

• DPF warning light

• Exhaust filter warning

• Emissions-system warning

• Regeneration required message

The exact warning depends on the vehicle.

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Reduced Engine Power

If the ECM/PCM determines that the DPF system is operating outside acceptable parameters, the vehicle may reduce engine output.

Possible symptoms include:

• Slow acceleration

• Reduced torque

• Limited RPM

• Reduced turbocharger response

• Poor high-load performance

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Limp Mode

Some vehicles can enter a reduced-power or limp-home mode when DPF-related faults become severe.

This is more likely when P2002 is accompanied by other DPF, exhaust pressure, regeneration, or engine-management codes.

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Poor Acceleration

A restricted DPF can increase exhaust backpressure and reduce engine performance.

The driver may notice:

• Sluggish acceleration

• Poor response under load

• Reduced high-RPM performance

• Difficulty accelerating uphill

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Increased Fuel Consumption

Repeated or unsuccessful regeneration attempts can increase fuel consumption.

The engine control system may modify fuel injection or other operating parameters to raise exhaust temperature.

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Frequent Regeneration

The vehicle may attempt regeneration more frequently than normal.

Possible signs include:

• Increased exhaust temperature

• Cooling fan operation after driving

• Elevated idle speed

• Increased fuel consumption

• Regeneration-related messages

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Excessive Exhaust Smoke or Soot

A healthy DPF should capture a significant amount of diesel particulate matter.

If the DPF substrate is cracked or damaged, excessive particulate matter may pass through the filter.

Visible soot or abnormal smoke can therefore be an important clue when investigating an efficiency-related DPF fault.

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Regeneration Problems

A vehicle with P2002 may have difficulty completing regeneration.

Possible symptoms include:

• Repeated regeneration requests

• Failed regeneration attempts

• Increasing DPF differential pressure

• Increasing calculated soot load

• DPF warning messages

• Reduced engine performance

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No Noticeable Symptoms

P2002 can sometimes be detected before the driver notices a significant change in engine operation.

The ECM may detect an efficiency problem while the vehicle is still operating relatively normally.

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Common Causes of P2002

Damaged DPF Substrate

A cracked or physically damaged DPF is an important possible cause of P2002.

The DPF substrate is responsible for trapping particulate matter.

If the substrate is damaged, exhaust gases can pass through areas that do not provide the intended filtration.

This can result in:

Reduced filtration → increased particulate output → DPF efficiency below threshold → P2002

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Melted DPF

Excessive exhaust temperature can damage the DPF substrate.

Possible causes include:

• Excessive fueling

• Abnormal regeneration

• Engine misfire

• Injector problems

• Incorrect injection timing

• Turbocharger problems

• Exhaust after-treatment faults

A melted substrate may no longer provide the required filtration.

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Excessive Soot Loading

A DPF heavily loaded with soot may not operate correctly.

Possible causes include:

• Frequent short trips

• Stop-and-go driving

• Repeated interrupted regenerations

• Low exhaust temperatures

• Faulty EGT sensors

• EGR problems

• Injector problems

• Turbocharger or boost problems

Excessive soot loading should be distinguished from permanent DPF substrate damage.

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Excessive Ash Accumulation

Ash accumulates over the life of the DPF and cannot normally be removed through ordinary regeneration.

A high ash load can reduce the usable capacity of the filter.

An older DPF may eventually require:

• Professional cleaning

• DPF service

• Replacement

The correct procedure depends on the manufacturer's specifications and the condition of the filter.

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Failed Regeneration

Repeatedly failed regeneration can leave excessive soot inside the DPF.

Possible causes include:

• Low exhaust temperature

• Faulty EGT sensor

• Faulty differential-pressure sensor

• Fuel-system problems

• EGR problems

• Incorrect regeneration control

• Short driving cycles

• Low engine load

• Exhaust leaks

The reason regeneration fails should be diagnosed rather than repeatedly forcing regeneration.

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Exhaust Leaks

An exhaust leak can interfere with exhaust-system measurements and DPF monitoring.

Possible leak locations include:

• Exhaust manifold

• Turbocharger connection

• DPF inlet

• DPF outlet

• Exhaust pipe

• Flex pipe

• Gaskets

• Sensor ports

An exhaust leak around the DPF pressure-sensing system is particularly important.

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Faulty DPF Differential-Pressure Sensor

The DPF differential-pressure sensor measures the pressure difference across the filter.

The ECM uses this information to estimate DPF restriction and loading.

A faulty sensor can produce incorrect DPF calculations.

Possible problems include:

• Internal sensor failure

• Incorrect sensor output

• Blocked pressure ports

• Damaged pressure hoses

• Cracked pressure hoses

• Condensation contamination

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Blocked DPF Pressure-Sensor Hoses

The sensor itself may be functional while the hoses connected to it are blocked.

Soot, condensation, or contamination can restrict the pressure lines.

This can result in incorrect differential-pressure readings and incorrect DPF calculations.

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Faulty Exhaust Gas Temperature Sensor

The ECM relies on accurate exhaust-temperature information for regeneration and after-treatment monitoring.

A faulty EGT sensor can cause:

• Incorrect regeneration control

• Failed regeneration

• Incorrect DPF monitoring

• Incorrect exhaust-temperature calculations

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Damaged Sensor Wiring

DPF sensors are exposed to heat, vibration, moisture, and contamination.

Wiring problems can include:

• Broken wires

• Chafed insulation

• Melted insulation

• Corrosion

• Short circuits

• Loose terminals

• Poor previous repairs

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Fuel Injector Problems

A leaking, contaminated, or incorrectly operating fuel injector can cause excessive fueling.

Excess fuel can increase soot production and place additional load on the DPF.

If the injector problem is not corrected, a replacement DPF may fail again.

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EGR System Problems

The EGR system affects combustion conditions and emissions.

An EGR fault can contribute to excessive particulate production.

Possible problems include:

• Stuck EGR valve

• Carbon buildup

• Faulty EGR actuator

• EGR cooler problems

• Incorrect EGR operation

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Turbocharger or Boost Problems

A turbocharger or boost problem can alter the engine's air-fuel balance.

Possible problems include:

• Low boost

• Boost leaks

• Variable geometry turbo problems

• Wastegate problems

• Turbocharger actuator problems

These conditions can increase soot production.

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Incorrect Engine Oil

DPF-equipped diesel engines often require specific low-ash engine oil.

Using an unsuitable oil can increase ash accumulation over time.

The oil specification should therefore match the manufacturer's requirements.

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Excessive Engine Soot Production

Sometimes the DPF is not the original source of the problem.

An engine producing excessive particulate matter can overload the DPF.

Possible causes include:

• Poor combustion

• Fuel-system problems

• Injector problems

• EGR faults

• Air intake restrictions

• MAF sensor problems

• Turbocharger problems

• Boost leaks

The underlying engine problem should be repaired before installing a new DPF.

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ECM/PCM Software or Calibration Problem

In some cases, a software or calibration issue can cause incorrect interpretation of DPF data.

Manufacturer technical information should be checked before replacing major components.

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How Is P2002 Diagnosed?

P2002 should be diagnosed systematically.

A useful diagnostic sequence is:

Scan → review freeze-frame data → inspect exhaust → verify sensors → evaluate regeneration → assess soot/ash loading → inspect DPF → repair root cause → verify operation

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Step 1: Scan for Additional Trouble Codes

Use a professional diagnostic scan tool to check for:

• Stored codes

• Pending codes

• History codes

• Freeze-frame data

Pay particular attention to codes involving:

• DPF

• Exhaust pressure

• EGT sensors

• Regeneration

• EGR

• Fuel injectors

• Turbocharger

• Airflow

• Exhaust after-treatment

Additional codes may identify the underlying problem.

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Step 2: Review Freeze-Frame Data

Review the operating conditions when P2002 was stored.

Depending on the vehicle, check:

• Engine RPM

• Engine load

• Vehicle speed

• Coolant temperature

• Exhaust temperature

• DPF differential pressure

• Calculated soot load

• Calculated ash load

• Regeneration status

• Regeneration history

This can help determine whether the problem occurs during regeneration or normal engine operation.

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Step 3: Check DPF Differential Pressure

Monitor the pressure difference across the DPF.

An abnormally high differential pressure can indicate:

• Excessive soot

• Excessive ash

• Severe restriction

• Incorrect exhaust flow

However, a normal differential pressure does not automatically prove that the DPF is healthy.

A damaged or cracked substrate can have poor filtration efficiency without creating the extreme restriction associated with a blocked filter.

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Step 4: Inspect the DPF Differential-Pressure Sensor

Check:

• Sensor

• Wiring

• Connector

• Pressure hoses

• Pressure ports

Make sure the hoses are:

• Connected correctly

• Not blocked

• Not cracked

• Not melted

• Not kinked

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Step 5: Verify EGT Sensor Operation

Monitor exhaust temperature data.

Look for:

• Implausible temperature readings

• Fixed readings

• Abnormally slow response

• Temperature values inconsistent with engine operation

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Step 6: Check for Exhaust Leaks

Inspect the exhaust system around the DPF.

Pay particular attention to:

• DPF inlet

• DPF outlet

• Gaskets

• Turbocharger connections

• Flex pipe

• Sensor ports

• Pressure-sensor connections

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Step 7: Check Regeneration History

Determine:

• When the last regeneration occurred

• Whether it completed successfully

• How frequently regeneration is occurring

• How many regeneration attempts failed

• Current calculated soot loading

Repeated failed regenerations indicate that an underlying problem may exist.

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Step 8: Check Calculated Soot Load

If scan-tool data is available, compare calculated soot loading with other DPF parameters.

An unusually high soot load may indicate:

• Regeneration failure

• Excessive soot production

• Low exhaust temperature

• Sensor problems

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Step 9: Check Calculated Ash Load

If the vehicle provides ash-load information, review it.

A high ash load on a high-mileage vehicle can indicate that the DPF is approaching the end of its useful service life.

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Step 10: Check Engine Operation

Investigate whether the engine is producing excessive soot.

Check:

• Fuel injectors

• Fuel pressure

• Air intake

• MAF sensor

• Turbocharger

• Boost pressure

• EGR system

• Engine combustion

• Intake restrictions

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Step 11: Check for Excessive Soot Output

Inspect the exhaust system for abnormal soot accumulation.

Excessive soot downstream of the DPF can be a significant clue that the filter substrate is damaged or that another engine problem is overwhelming the filter.

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Step 12: Inspect the DPF Physically

If sensor and engine tests do not identify the problem, inspect the DPF itself.

Depending on the vehicle, the filter may need to be removed.

Check for:

• Cracked substrate

• Melted substrate

• Broken substrate

• Severe ash accumulation

• Physical damage

• Abnormal discoloration

• Contamination

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Step 13: Check Manufacturer Technical Information

Before replacing the DPF, check for:

• Technical Service Bulletins

• Known DPF problems

• Sensor updates

• Pressure-hose problems

• Regeneration procedures

• Software updates

• DPF replacement procedures

• Required reset procedures

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Step 14: Verify DPF Efficiency After Repair

After the underlying problem has been repaired, verify:

• DPF differential pressure

• Exhaust temperatures

• Soot loading

• Regeneration operation

• Engine performance

• Exhaust after-treatment data

Clear the code and complete the appropriate drive cycle.

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How to Fix P2002

The correct repair depends on the actual cause.

Repair an Exhaust Leak

Repair leaks around the DPF and exhaust system.

Possible repairs include:

• Replacing gaskets

• Repairing exhaust pipes

• Replacing damaged flex sections

• Tightening loose connections

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Replace the DPF Differential-Pressure Sensor

If testing confirms that the pressure sensor is inaccurate, replace it.

The pressure hoses and ports should also be checked.

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Repair or Replace Pressure-Sensor Hoses

Blocked, cracked, melted, or incorrectly connected pressure hoses should be repaired or replaced according to the manufacturer's procedure.

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Replace a Faulty EGT Sensor

If an exhaust gas temperature sensor is defective, replace it and verify the temperature readings afterward.

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Repair Sensor Wiring

Electrical repairs may include:

• Repairing broken wires

• Replacing damaged terminals

• Repairing connectors

• Correcting poor grounds

• Replacing heat-damaged wiring

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Perform a Manufacturer-Approved Regeneration

If excessive soot loading is confirmed and the DPF remains serviceable, a manufacturer-approved regeneration may restore normal operation.

However, a forced regeneration should not be performed blindly.

If the DPF is severely restricted or damaged, forcing regeneration can produce extremely high exhaust temperatures and potentially damage the DPF, turbocharger, or other exhaust components.

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Professional DPF Cleaning

If excessive ash accumulation is present and the DPF is serviceable, professional cleaning may be appropriate.

The filter should be inspected before deciding that cleaning is sufficient.

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Replace the Damaged DPF

DPF replacement may be necessary when testing confirms:

• Cracked substrate

• Melted substrate

• Broken substrate

• Severe physical damage

• Irreparable filtration failure

• Excessive ash accumulation that cannot be appropriately serviced

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Repair the Underlying Engine Problem

If excessive soot production caused the DPF problem, repair the engine first.

Possible repairs include:

• Fuel injector replacement

• EGR repair

• Turbocharger repair

• Boost leak repair

• MAF sensor replacement

• Fuel-system repair

• Air-intake repair

Replacing only the DPF without correcting excessive soot production can cause the replacement filter to fail again.

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Update ECM/PCM Software

If manufacturer service information identifies a software or calibration issue, update the ECM/PCM according to the approved procedure.

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Reset DPF Adaptations When Required

Some vehicles require an adaptation or reset procedure after replacing the DPF or related sensors.

Depending on the vehicle, this may include:

• DPF replacement reset

• Ash-load reset

• Differential-pressure sensor relearn

• Regeneration adaptation

• Exhaust after-treatment reset

The correct procedure is vehicle-specific.

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P2002 vs. P2003

These codes describe the same general DPF efficiency condition on different cylinder banks.

Code	Meaning
P2002	Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
P2003	Diesel Particulate Filter Efficiency Below Threshold (Bank 2)

The key difference is:

P2002 = Bank 1

P2003 = Bank 2

If both P2002 and P2003 are stored, investigate whether a common problem is affecting both banks.

Possible common causes include:

• Incorrect regeneration

• Engine producing excessive soot

• Fuel-system problems

• EGR problems

• Turbocharger problems

• Exhaust-system problems

• Sensor problems

• Incorrect DPF monitoring

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P2002 vs. P2004

Code	Meaning
P2002	Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
P2004	Intake Manifold Runner Control Stuck Open (Bank 1)

These codes concern different systems.

P2002 = DPF efficiency problem

P2004 = Intake manifold runner problem

P2004 should not be used as evidence that the DPF is defective.

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P2002 vs. P2005

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2005	Intake Manifold Runner Control Stuck Open (Bank 2)

P2002 concerns the DPF on Bank 1.

P2005 concerns the intake manifold runner control system on Bank 2.

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P2002 vs. P2006

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2006	Intake Manifold Runner Control Stuck Closed (Bank 1)

Both identify Bank 1, but they involve different components.

P2002 concerns DPF filtration efficiency.

P2006 concerns a Bank 1 intake runner stuck closed.

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P2002 vs. P2007

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2007	Intake Manifold Runner Control Stuck Closed (Bank 2)

P2002 = Bank 1 DPF efficiency below threshold.

P2007 = Bank 2 intake runner stuck closed.

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P2002 vs. P2008

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2008	Intake Manifold Runner Control Circuit/Open (Bank 1)

P2002 concerns DPF performance.

P2008 concerns an open Bank 1 intake runner-control circuit.

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P2002 vs. P2009

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2009	Intake Manifold Runner Control Circuit Low (Bank 1)

P2002 = DPF efficiency problem.

P2009 = Bank 1 IMRC circuit low.

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P2002 vs. P2010

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2010	Intake Manifold Runner Control Circuit High (Bank 1)

P2002 concerns the DPF.

P2010 concerns a high electrical condition in the Bank 1 IMRC circuit.

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P2002 vs. P2011

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2011	Intake Manifold Runner Control Circuit/Open (Bank 2)

P2002 = Bank 1 DPF efficiency below threshold.

P2011 = Bank 2 IMRC circuit open.

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P2002 vs. P2012

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2012	Intake Manifold Runner Control Circuit Low (Bank 2)

P2002 concerns Bank 1 DPF efficiency.

P2012 concerns Bank 2 IMRC circuit low.

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P2002 vs. P2013

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2013	Intake Manifold Runner Control Circuit High (Bank 2)

P2002 = Bank 1 DPF efficiency.

P2013 = Bank 2 IMRC circuit high.

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P2002 vs. P2014

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2014	Intake Manifold Runner Position Sensor / Switch Circuit (Bank 1)

P2002 concerns DPF filtration.

P2014 concerns the Bank 1 intake runner position-sensor/switch circuit.

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P2002 vs. P2015

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2015	Intake Manifold Runner Position Sensor / Switch Circuit Range / Performance (Bank 1)

P2002 = DPF efficiency below threshold.

P2015 = Bank 1 intake runner position-sensor/switch range or performance problem.

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P2002 vs. P2016

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2016	Intake Manifold Runner Position Sensor / Switch Circuit Low (Bank 1)

P2002 concerns the DPF.

P2016 concerns a low Bank 1 runner position-sensor/switch circuit signal.

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P2002 vs. P2017

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2017	Intake Manifold Runner Position Sensor / Switch Circuit High (Bank 1)

P2002 = Bank 1 DPF efficiency below threshold.

P2017 = Bank 1 runner position-sensor/switch circuit high.

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P2002 vs. P2018

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2018	Intake Manifold Runner Position Sensor / Switch Circuit Intermittent (Bank 1)

P2002 concerns DPF efficiency.

P2018 concerns an intermittent Bank 1 runner position-sensor/switch circuit.

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P2002 vs. P2019

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2019	Intake Manifold Runner Position Sensor / Switch Circuit Malfunction (Bank 2)

P2002 concerns the Bank 1 DPF.

P2019 concerns the Bank 2 intake runner position-sensor/switch circuit.

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P2002 vs. P2020

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2020	Intake Manifold Runner Position Sensor / Switch Circuit Range / Performance (Bank 2)

P2002 = Bank 1 DPF efficiency problem.

P2020 = Bank 2 runner position-sensor/switch range or performance problem.

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P2002 vs. P2021

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2021	Intake Manifold Runner Position Sensor / Switch Circuit Low (Bank 2)

P2002 concerns Bank 1 DPF efficiency.

P2021 concerns Bank 2 runner position-sensor/switch circuit low.

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P2002 vs. P2022

Code	Meaning
P2002	DPF Efficiency Below Threshold (Bank 1)
P2022	Intake Manifold Runner Position Sensor / Switch Circuit High (Bank 2)

P2002 = Bank 1 DPF efficiency.

P2022 = Bank 2 runner position-sensor/switch circuit high.

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P2002 vs. P2023

Code	Meaning
P2002	Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
P2023	Intake Manifold Runner Position Sensor / Switch Circuit Intermittent (Bank 2)

P2002 concerns DPF efficiency on Bank 1.

P2023 concerns an intermittent Bank 2 intake runner position-sensor/switch circuit.

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Can You Drive With P2002?

Short-distance driving may be possible if the vehicle is operating normally, but P2002 should not be ignored.

The consequences depend on the underlying problem.

If the fault is caused by a sensor or pressure-sensor hose, the DPF itself may still be healthy.

If the DPF is severely restricted, damaged, or repeatedly failing regeneration, continued driving can make the problem worse.

Possible consequences include:

• Increasing soot loading

• Increasing exhaust backpressure

• More frequent regeneration

• Reduced engine power

• Limp mode

• Increased fuel consumption

• DPF damage

• Turbocharger stress in severe cases

• Increased emissions

If the vehicle has severe power loss, repeated regeneration failures, a DPF warning, or other serious engine-management symptoms, it should be inspected promptly.

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Is P2002 a Serious Code?

P2002 can range from moderate to serious depending on the cause.

A faulty DPF pressure sensor or blocked pressure hose may be relatively straightforward to repair.

A cracked, melted, or severely ash-loaded DPF can be considerably more serious.

The key diagnostic question is:

Is the DPF actually damaged, or is the ECM receiving incorrect information about DPF operation?

This distinction can prevent unnecessary DPF replacement.

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How to Prevent P2002

Proper diesel engine and DPF maintenance can reduce the risk of DPF efficiency problems.

Recommended practices include:

• Follow the manufacturer's maintenance schedule.

• Use the correct low-ash engine oil when specified.

• Avoid repeatedly using a DPF-equipped diesel only for very short trips.

• Allow automatic regeneration to complete when operating conditions permit.

• Avoid unnecessarily interrupting regeneration.

• Repair fuel injector problems promptly.

• Maintain the EGR system.

• Maintain the turbocharger and boost system.

• Repair exhaust leaks quickly.

• Inspect DPF pressure-sensor hoses.

• Address faulty EGT sensors.

• Do not ignore DPF warning messages.

• Address Check Engine Light warnings promptly.

• Use the correct fuel and engine oil specifications.

• Avoid repeatedly forcing regeneration without diagnosing why soot loading is excessive.

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Final Thoughts

P2002 Diesel Particulate Filter (DPF) Efficiency Below Threshold (Bank 1) indicates that the ECM/PCM has determined that the Bank 1 DPF is not providing the expected level of particulate filtration efficiency.

The most important point is that P2002 does not automatically mean the DPF is clogged or needs to be replaced.

Possible causes include:

• Cracked or damaged DPF substrate

• Melted DPF

• Excessive soot accumulation

• Excessive ash accumulation

• Failed regeneration

• Exhaust leaks

• Faulty DPF differential-pressure sensor

• Blocked pressure-sensor hoses

• Faulty EGT sensor

• Damaged sensor wiring

• Fuel injector problems

• EGR problems

• Turbocharger or boost problems

• Excessive engine soot production

• Incorrect engine oil

• ECM/PCM software or calibration problems

Diagnosis should begin with a complete scan and freeze-frame analysis.

The DPF differential-pressure sensor and its hoses should then be inspected, followed by exhaust leak checks and EGT sensor verification.

The technician should evaluate regeneration history, calculated soot and ash loading, and the engine's ability to operate without producing excessive particulate matter.

It is particularly important to distinguish DPF restriction from DPF filtration efficiency.

A heavily blocked DPF generally produces increased differential pressure, while a cracked or physically damaged DPF substrate can allow particulate matter to pass through even when restriction is not extremely high.

Therefore, normal differential pressure does not automatically prove that the DPF is healthy.

Before replacing the DPF, verify the pressure sensor, pressure hoses, temperature sensors, exhaust system, regeneration operation, fuel system, EGR system, turbocharger, and overall engine condition.

If the DPF substrate is confirmed to be cracked, melted, broken, severely damaged, or unable to provide the required filtration efficiency, replacement may be necessary.

If the DPF is serviceable but heavily loaded with soot or ash, a manufacturer-approved regeneration or professional DPF cleaning may be appropriate, depending on the vehicle and filter condition.

After the repair, complete any required DPF replacement reset, adaptation, sensor relearn, or regeneration procedure.

Finally, clear P2002, complete the appropriate drive cycle, monitor DPF pressure and exhaust-temperature data, and rescan the vehicle.

The final verification should confirm that the Bank 1 DPF is operating within the expected efficiency range and that P2002 does not return.