P244B Diesel Particulate Filter (DPF) Differential Pressure Too High Bank 1

P244B indicates that the engine control module (ECM/PCM) has detected excessive differential pressure across the Diesel Particulate Filter (DPF) on Bank 1.

In simple terms, the control system believes that exhaust gases are encountering more resistance than expected when passing through the DPF.

A DPF is designed to trap soot from diesel exhaust. As soot accumulates, exhaust backpressure naturally increases. During a successful regeneration, the accumulated soot is burned and the pressure difference should decrease.

P244B means the measured or calculated pressure difference has exceeded the level the control system considers acceptable.

However, this does not automatically mean that the DPF itself must be replaced. A heavily loaded filter is one possibility, but the differential pressure sensor, pressure hoses, wiring, exhaust leaks, incorrect sensor readings, regeneration problems and engine conditions can also produce this code.

What Is DPF Differential Pressure?

The DPF sits in the exhaust system and captures particulate matter, commonly called soot.

As exhaust gas passes through the filter, the filter creates some resistance.

The ECM monitors this resistance using a DPF differential pressure sensor.

The sensor typically receives pressure information from two points:

• Before the DPF

• After the DPF

The difference between these two pressures is called differential pressure.

When the DPF is relatively clean, the pressure difference is generally lower.

As soot accumulates, the restriction increases and the pressure difference rises.

Therefore, differential pressure is one of the important parameters the ECM uses to estimate DPF loading and determine whether regeneration is necessary.

What Does “Too High” Mean?

The phrase “Differential Pressure Too High” refers to the pressure difference across the DPF being higher than the calibrated limit under the operating conditions being monitored.

It does not necessarily mean that the absolute pressure before the DPF is always extremely high.

The ECM is comparing the pressure upstream of the filter with the pressure downstream.

If the difference becomes excessive, the ECM can interpret this as a restriction.

A useful simplified example is:

High pressure before DPF + relatively lower pressure after DPF = high differential pressure

The actual pressure values and diagnostic thresholds vary by engine and manufacturer.

What Is Bank 1?

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

On an inline diesel engine, there is normally only one cylinder bank, so the DPF system is generally associated with Bank 1.

On a V-type diesel engine, there can be separate exhaust systems for Bank 1 and Bank 2.

The exact DPF configuration varies considerably between vehicles, so the manufacturer's exhaust layout should be checked before diagnosing the code.

Why Does DPF Pressure Increase?

A DPF is supposed to accumulate soot.

The problem occurs when soot accumulation becomes excessive or when the filter cannot regenerate properly.

During normal operation, soot gradually builds up inside the filter.

The vehicle then initiates DPF regeneration.

During regeneration, exhaust temperatures are increased sufficiently to oxidize accumulated soot and reduce the filter's loading.

If regeneration repeatedly fails, the amount of soot can continue increasing.

Eventually, exhaust flow through the filter becomes restricted and differential pressure rises.

This is one of the most common pathways leading to P244B.

Common Causes of P244B

DPF overloaded with soot

A DPF that contains excessive soot can create significant exhaust restriction.

This can happen after repeated failed regenerations or extensive low-speed driving.

Repeated interrupted regeneration

If regeneration starts but is repeatedly interrupted before completion, soot can continue accumulating.

Frequent short trips are particularly unfavorable for some diesel vehicles because the exhaust system may not remain at the required operating temperature long enough for regeneration to complete.

Failed DPF regeneration system

The engine may be unable to achieve or maintain the temperature necessary for regeneration.

Possible causes include:

• Faulty temperature sensor

• Fuel-injection problem

• Failed regeneration injector where equipped

• Exhaust throttle problem

• EGR-related issue

• Glow-plug system problem on some vehicles

• Engine operating-temperature problem

• Incorrect regeneration control

Blocked DPF differential pressure hoses

The pressure sensor relies on small hoses or tubes connected to the exhaust.

Soot, condensation and other deposits can partially or completely block these passages.

A blocked hose can cause the sensor to report an incorrect pressure difference.

Damaged pressure hoses

A cracked, melted, disconnected or incorrectly routed pressure hose can also produce incorrect readings.

Defective DPF differential pressure sensor

The sensor itself may fail or become inaccurate.

If it reports excessive pressure when the DPF is not actually restricted, the ECM can set P244B even though the filter is not the real problem.

Sensor wiring or connector problem

Electrical problems can interfere with the pressure sensor signal.

Possible problems include:

• Corrosion

• Loose terminals

• Broken wires

• Short circuits

• Damaged connectors

• Poor ground

• Water intrusion

Ash accumulation

Soot can be burned during regeneration, but ash is different.

Ash comes from engine oil additives and other non-combustible materials and gradually accumulates in the DPF over the vehicle's lifetime.

A DPF can therefore become restricted even when regeneration is functioning normally.

Engine producing excessive soot

The DPF may simply be doing its job while the engine is producing far more particulate matter than it should.

Potential causes include:

• Poor fuel injection

• Faulty injectors

• Incorrect air-fuel mixture

• Turbocharger problems

• Excessive EGR

• Intake restriction

• MAF sensor problems

• MAP sensor problems

• Poor combustion

• Excessive oil consumption

If the underlying engine problem is not repaired, cleaning or replacing the DPF may only provide temporary relief.

P244B Symptoms

The symptoms depend on how restricted the DPF has become and how the vehicle's control system responds.

Possible symptoms include:

• Check Engine Light

• DPF warning light

• Reduced engine power

• Limp-home mode

• Poor acceleration

• Increased fuel consumption

• More frequent regeneration

• Regeneration that takes unusually long

• Regeneration that repeatedly fails

• Increased exhaust temperature

• Engine fan operating more frequently

• Turbocharger performance problems

• Rough running in some cases

• Difficulty maintaining engine speed under load

A mildly elevated differential pressure may produce little noticeable change in drivability.

A severely restricted DPF can have a dramatic effect on engine performance.

A Blocked DPF Is Not the Only Possibility

This is one of the most important aspects of P244B diagnosis.

Suppose the DPF differential pressure sensor is defective.

The actual exhaust pressure may be normal, but the sensor could report an artificially high pressure difference.

The ECM sees the sensor value and concludes that the DPF is restricted.

The result can be P244B even though the filter itself is not blocked.

The same principle applies to the pressure hoses.

If one hose is blocked with soot or condensation, the sensor may receive incorrect pressure information.

Therefore:

P244B does not automatically mean “replace the DPF.”

How to Diagnose P244B

A proper diagnosis should begin with the data rather than the DPF itself.

Scan for all related DTCs

First, perform a complete scan and record all stored and pending codes.

Look for codes related to:

• DPF regeneration

• Differential pressure sensor

• Exhaust temperature

• EGR

• MAF

• MAP

• Turbocharger

• Fuel injection

• Glow plugs

• Exhaust pressure

• Engine temperature

If several related codes are present, they should be considered together.

A regeneration failure code appearing alongside P244B can be particularly important.

Check the DPF Differential Pressure Sensor

The sensor should be inspected before condemning the filter.

Check:

• Electrical connector

• Wiring

• Pressure ports

• Sensor mounting

• Pressure hoses

• Hose routing

• Signs of contamination

• Signs of heat damage

The two pressure lines should be checked for blockage, cracks, melting, disconnection and incorrect installation.

Inspect the Pressure Hoses Carefully

The small pressure hoses connected to the DPF differential pressure sensor are easy to overlook.

They can accumulate soot and condensation.

A hose can also become brittle from heat.

If one hose is blocked while the other remains open, the sensor can produce a misleading pressure differential.

The hoses should be inspected and tested according to the manufacturer's procedure rather than simply blowing into them or replacing parts without knowing the system design.

Check Live Differential Pressure Data

A scan tool capable of reading manufacturer-specific live data can be extremely useful.

The technician can monitor DPF differential pressure under different engine conditions.

The important question is not simply:

“Is the pressure high?”

Instead, ask:

“Does the measured pressure behave correctly for engine speed and load?”

A pressure reading that increases sharply with engine speed and load may support a genuine exhaust restriction.

An implausible or unstable reading can point toward the sensor or pressure lines.

Exact acceptable values vary by engine, DPF design and operating conditions, so generic internet pressure numbers should not be treated as universal specifications.

Check DPF Soot and Ash Calculations

Many modern diesel systems calculate estimated DPF loading.

Diagnostic equipment may provide parameters such as:

• Calculated soot mass

• Estimated soot load

• Ash accumulation

• Distance since last regeneration

• Time since last regeneration

• Regeneration status

• Regeneration request

• Regeneration completion

• Differential pressure

These values can help determine whether the filter is genuinely overloaded.

If the calculated soot load is extremely high and differential pressure is also high, DPF restriction becomes more credible.

If the calculated soot load is normal but the differential-pressure value is extreme, the sensor circuit deserves closer investigation.

Determine Why Regeneration Is Failing

If the DPF is genuinely overloaded, the next question is:

Why did it become overloaded?

A DPF does not normally become severely restricted without some reason.

Possible reasons include:

• Vehicle used mainly for short journeys

• Repeatedly interrupted regeneration

• Engine not reaching normal operating temperature

• Faulty exhaust temperature sensor

• Fuel injection problem

• EGR malfunction

• Turbocharger problem

• Intake restriction

• Excessive engine soot production

• Low-quality or incorrect engine oil

• Regeneration control fault

Simply forcing another regeneration without finding the reason for the excessive soot accumulation can result in the same problem returning.

Forced DPF Regeneration

A service tool may offer a forced or stationary DPF regeneration procedure.

This should not be treated as a universal solution.

If the DPF is only moderately loaded and the rest of the system is healthy, a manufacturer-approved regeneration procedure may successfully reduce soot accumulation.

But if the filter is severely restricted, damaged or heavily loaded with ash, forcing regeneration can be inappropriate or dangerous.

A regeneration also produces extremely high exhaust temperatures.

The procedure must therefore follow the manufacturer's requirements concerning:

• Engine condition

• Fuel level

• Coolant temperature

• Oil condition

• Vehicle location

• Exhaust clearance

• Fire risk

• DPF loading limits

Soot and Ash Are Not the Same

This distinction is critical when discussing DPF cleaning.

Soot is combustible.

Under appropriate regeneration conditions, soot can be oxidized and removed.

Ash is non-combustible.

Regeneration does not burn ash away.

Over time, ash accumulation can reduce the filter's effective capacity and increase exhaust restriction.

This means a high-mileage DPF can eventually require professional cleaning or replacement even if the vehicle's regeneration system is functioning correctly.

Can DPF Cleaning Fix P244B?

It can, but only when the DPF itself is genuinely restricted and the filter is suitable for cleaning.

Professional DPF cleaning can sometimes remove accumulated ash and particulate material that normal regeneration cannot eliminate.

However, cleaning the filter does not repair:

• A defective differential pressure sensor

• Blocked pressure hoses

• Damaged wiring

• Faulty temperature sensors

• Injector problems

• EGR problems

• Turbocharger faults

• Regeneration-control problems

If the underlying cause remains, the cleaned DPF may become restricted again.

What Happens If You Continue Driving?

The consequences depend on the severity of the restriction.

A moderately restricted DPF may allow the vehicle to continue operating for some time.

As restriction increases, exhaust backpressure can become a serious problem.

The engine may enter a reduced-power strategy to protect itself and the emissions system.

A severely restricted exhaust can contribute to:

• Major power loss

• Increased exhaust temperature

• Turbocharger stress

• Poor combustion

• Increased fuel consumption

• Failed regeneration attempts

• Engine protection mode

Therefore, P244B should not be ignored, particularly when accompanied by a DPF warning light or noticeable power reduction.

When Should You Stop Driving?

A vehicle with P244B should be checked promptly if the warning is accompanied by significant symptoms.

Avoid continuing to drive under heavy load if there is:

• Severe loss of power

• DPF warning indicating critical loading

• Excessive exhaust temperature

• Heavy smoke

• Engine overheating

• Severe turbocharger symptoms

• Limp mode

• Multiple related engine-management warnings

If the vehicle is severely restricted, continuing to operate it can turn a manageable emissions-system problem into a much more expensive repair.

P244B vs DPF Soot Load Codes

P244B should also be distinguished from codes that specifically indicate excessive soot accumulation.

A DPF differential pressure code is based on pressure behavior across the filter.

A DPF soot accumulation code may be based primarily on the ECM's calculated or measured soot load.

The two conditions can occur together, but they are not identical.

For example, a faulty pressure sensor can create a differential-pressure fault without the DPF actually being heavily loaded.

Likewise, a DPF can have significant soot accumulation before the pressure reaches the threshold associated with a particular DTC.

P244B and the Differential Pressure Sensor

The DPF differential pressure sensor is one of the most important components to investigate.

It essentially acts as the ECM's pressure measurement system for the filter.

If it reports an incorrect differential pressure, the ECM may make incorrect decisions regarding:

• DPF loading

• Regeneration

• Exhaust restriction

• Emissions control

The sensor therefore deserves proper electrical and pressure testing rather than being replaced simply because it is associated with the code.

Possible Repairs for P244B

The correct repair depends on the confirmed cause.

Possible repairs include:

• Repairing or replacing blocked DPF pressure hoses

• Replacing a defective differential pressure sensor

• Repairing damaged sensor wiring

• Repairing connector terminals

• Cleaning a moderately loaded DPF when appropriate

• Professionally cleaning an ash-loaded DPF

• Replacing a damaged or exhausted DPF

• Repairing exhaust temperature sensors

• Correcting injector problems

• Repairing EGR faults

• Correcting turbocharger problems

• Repairing intake restrictions

• Fixing engine-temperature problems

• Correcting the underlying cause of excessive soot production

The DPF itself should be replaced only when testing confirms that cleaning or regeneration is not an appropriate solution.

Why Replacing the DPF First Can Be a Mistake

Imagine replacing an expensive DPF while the actual problem is a defective differential pressure sensor.

The new filter is installed.

The sensor continues reporting an incorrect high pressure.

P244B returns.

The new DPF has now been replaced unnecessarily, while the original electrical problem remains.

The opposite situation is also possible.

If an engine is producing excessive soot because of a faulty injector, installing a new DPF without repairing the injector can simply load the replacement filter again.

The correct sequence is therefore:

Measure → verify → identify the cause → repair the cause → confirm the result.

Is P244B Serious?

P244B can become a serious fault if the differential pressure is genuinely too high.

A small increase in DPF restriction is not necessarily an immediate engine emergency.

But a severely restricted DPF can significantly interfere with exhaust flow and engine operation.

The urgency increases when the code appears together with a DPF warning, reduced power, failed regeneration, high exhaust temperatures or additional engine-management faults.

The Bottom Line

P244B – Diesel Particulate Filter (DPF) Differential Pressure Too High Bank 1 means the ECM has detected an excessive pressure difference across the DPF.

The most obvious possibility is a DPF that is heavily loaded or restricted, but that is not the only explanation.

The differential pressure sensor, its pressure hoses, wiring, regeneration system and the engine's ability to produce clean combustion all need to be considered.

A good diagnosis should establish whether the high pressure is real or only being reported incorrectly.

If the DPF is genuinely restricted, determine whether the restriction is caused by soot, ash or an underlying engine/regeneration problem. A proper regeneration or professional cleaning may solve the problem in some cases, while a severely damaged or exhausted filter may require replacement.

The DPF is the component receiving the pressure, but the real fault may be somewhere else in the system.