P2046 Reductant Temperature Sensor Circuit Intermittent

P2046 Reductant Temperature Sensor Circuit Intermittent is a generic OBD-II diagnostic trouble code indicating that the Engine Control Module (ECM), Powertrain Control Module (PCM), or aftertreatment control module has detected an intermittent electrical problem in the reductant temperature sensor circuit.

In simple terms, the vehicle's computer is receiving an unstable, inconsistent, or occasionally missing signal from the sensor that monitors the temperature of the reductant fluid, such as Diesel Exhaust Fluid (DEF) or AdBlue.

The reductant temperature sensor is an important part of the Selective Catalytic Reduction (SCR) system. The control module uses reductant temperature information to determine whether the fluid is frozen, at normal operating temperature, or outside the expected temperature range. It can also use this information when controlling reductant heating, pumping, dosing, and emissions-system operation.

The word "Intermittent" is especially important. Unlike a permanent open or short circuit, an intermittent fault may appear and disappear depending on:

• Temperature

• Vibration

• Harness movement

• Connector condition

• Moisture

• Ice formation

• Electrical load

• Sensor temperature

As a result, P2046 can sometimes be difficult to diagnose because the circuit may test normally when the vehicle is stationary.

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What Does P2046 Mean?

The code description contains several important terms.

Reductant

Reductant is the fluid used by an SCR system to reduce nitrogen oxide (NOx) emissions.

On many diesel vehicles, this fluid is:

• Diesel Exhaust Fluid (DEF)

• AdBlue

• A urea-based reductant

DEF/AdBlue is injected into the exhaust system, where it participates in the chemical process that allows the SCR catalyst to convert NOx into primarily nitrogen and water.

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Temperature Sensor

The reductant temperature sensor measures the temperature of the DEF/AdBlue or the temperature associated with the reductant tank/module.

The sensor allows the control system to determine the thermal condition of the reductant.

This information can be important because DEF can freeze at approximately −11°C (12°F).

When the fluid is frozen, the SCR system may use heaters and other strategies to restore the system to an operating condition.

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Circuit

The circuit includes more than just the sensor itself.

Depending on the vehicle, it can include:

• Temperature sensor

• Sensor wiring

• Connector

• Reference-voltage circuit

• Ground circuit

• Signal circuit

• Reductant tank module

• Control module

An intermittent problem anywhere in this circuit can trigger P2046.

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Intermittent

"Intermittent" means that the control module has detected the fault sporadically rather than continuously.

For example, a damaged wire may work normally when stationary but lose electrical contact when the vehicle hits a bump.

Similarly, a corroded connector may make proper contact when cold but develop an unstable signal as temperature changes.

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How Does the Reductant Temperature Sensor Work?

Many reductant temperature sensors use a thermistor, typically an NTC (Negative Temperature Coefficient) thermistor.

In an NTC thermistor:

• Temperature increases → resistance generally decreases

• Temperature decreases → resistance generally increases

The control module measures the resulting electrical signal and calculates the approximate reductant temperature.

A simplified example is:

Cold DEF → higher sensor resistance → different signal voltage

Warm DEF → lower sensor resistance → different signal voltage

The actual resistance, voltage, and temperature relationship varies by manufacturer.

Therefore, a generic resistance value should not be used to diagnose every vehicle.

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Why Does the SCR System Need Reductant Temperature Information?

DEF/AdBlue has specific physical and chemical characteristics that change with temperature.

The control system needs to know the reductant's thermal condition to manage:

• Reductant heating

• Pump operation

• Dosing strategy

• Freeze protection

• SCR operation

• Diagnostic monitoring

If the temperature signal suddenly changes from a realistic value to an impossible or unstable value, the control module may recognize the signal as intermittent and store P2046.

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Symptoms of P2046

The symptoms can vary significantly depending on the vehicle and whether the fault is currently active.

Check Engine Light

The Check Engine Light may illuminate when the control module detects repeated intermittent faults.

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DEF/AdBlue Warning

The vehicle may display a reductant-system warning such as:

• Check DEF

• Check AdBlue

• DEF system fault

• AdBlue system fault

• Exhaust fluid system fault

• SCR system fault

• Emissions system fault

The exact wording depends on the manufacturer.

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Incorrect Reductant Temperature Reading

A scan tool may show a reductant temperature that suddenly:

• Jumps up

• Drops down

• Becomes implausible

• Changes rapidly without a corresponding physical temperature change

• Becomes unavailable

For example, if the vehicle has been parked overnight in cold weather, the reductant temperature should not suddenly indicate an extremely high temperature immediately after startup.

An unrealistic value can be an important diagnostic clue.

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Reductant Heater Problems

If the temperature signal is unreliable, the control module may have difficulty controlling the reductant heating system correctly.

Possible results include:

• Heater activation problems

• Longer warm-up periods

• Incorrect heater operation

• Additional reductant-heater codes

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SCR Performance Problems

An incorrect temperature signal can affect reductant-system control and may eventually contribute to SCR performance problems.

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Reduced Engine Power

Some diesel vehicles may reduce engine torque when persistent emissions-system faults are detected.

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Speed Limitation or Countdown

Depending on the vehicle and emissions strategy, a persistent SCR fault may eventually result in:

• Speed limitation

• Restart restrictions

• A DEF/AdBlue countdown

• Other operating restrictions

The exact strategy varies by manufacturer.

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No Noticeable Driving Symptoms

An intermittent P2046 may initially produce no noticeable driving problem.

The vehicle may operate normally while the control module records the fault in the background.

This is common with intermittent electrical problems.

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Common Causes of P2046

Damaged Wiring

Wiring damage is one of the most common possibilities for an intermittent sensor-circuit fault.

The harness can be affected by:

• Vibration

• Heat

• Abrasion

• Road debris

• Water

• Salt

• Repeated movement

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Chafed Wiring

A wire rubbing against:

• Tank brackets

• Chassis components

• Exhaust components

• Heat shields

• Mounting brackets

can develop damaged insulation.

The conductor may intermittently contact ground or another circuit.

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Loose Connector

A connector that is not fully locked can produce an intermittent signal.

The vehicle may appear to operate normally until:

• Vibration occurs

• The harness moves

• Temperature changes

• Moisture enters the connector

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Corroded Connector Terminals

Corrosion increases electrical resistance and can cause unstable sensor signals.

Inspect for:

• Green corrosion

• White deposits

• Rust

• Moisture

• Bent terminals

• Loose pins

• Damaged seals

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Water Intrusion

Moisture inside a reductant temperature sensor connector can cause intermittent electrical behavior.

This is particularly important on vehicles exposed to:

• Rain

• Snow

• Road salt

• Pressure washing

• Water crossings

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Faulty Reductant Temperature Sensor

The sensor itself can develop an internal fault.

Possible problems include:

• Internal resistance changing incorrectly

• Intermittent open circuit

• Internal short

• Unstable temperature signal

• Sensor degradation

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Faulty Reductant Tank Module

On some vehicles, the temperature sensor may be integrated into the reductant tank or tank module.

In such cases, the sensor may not be separately replaceable.

A tank module or related assembly may therefore require replacement if the sensor is confirmed defective.

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Wiring Inside the Reductant Tank

Some reductant tank assemblies contain internal wiring.

An intermittent internal connection can be difficult to diagnose from outside the tank.

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Poor Ground

A poor sensor ground can cause the signal to fluctuate.

Possible causes include:

• Corrosion

• Loose ground connection

• Damaged ground wire

• High-resistance connection

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Reference Voltage Problem

If the temperature sensor uses a reference-voltage circuit, instability in that supply can affect the temperature signal.

Possible causes include:

• Wiring damage

• Connector problems

• Shared sensor-circuit fault

• Control-module issue

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Electrical Interference From Another Circuit

A damaged wire may intermittently contact another circuit and cause an abnormal sensor reading.

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Frozen DEF/AdBlue

Frozen DEF can be relevant to reductant temperature diagnostics, particularly in cold conditions.

However, normal DEF freezing does not by itself mean the temperature sensor is defective.

The sensor should accurately report the cold condition.

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DEF Contamination

Incorrect or contaminated fluid can cause problems within the reductant system, but contamination is not normally the primary cause of an intermittent electrical circuit code.

The sensor circuit should therefore be inspected before blaming the DEF itself.

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Faulty Control Module

In rare cases, the ECM, PCM, or aftertreatment control module may have an internal fault affecting the sensor circuit.

The module should only be considered after the sensor, wiring, connectors, power supply, and ground have been properly tested.

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Software or Calibration Problem

A software or calibration issue can occasionally cause incorrect sensor interpretation or diagnostic monitoring.

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Vehicles Commonly Affected by P2046

P2046 can occur on diesel vehicles equipped with SCR and reductant temperature monitoring.

Examples may include:

• Ford F-250 Super Duty

• Ford F-350 Super Duty

• Ford F-450 Super Duty

• Ford Transit Diesel

• Chevrolet Silverado Duramax

• Chevrolet Express Diesel

• GMC Sierra Duramax

• GMC Savana Diesel

• Ram 2500

• Ram 3500

• Mercedes-Benz Sprinter

• Volkswagen Touareg TDI

• Volkswagen Transporter

• Audi Q7 TDI

• BMW X5 Diesel

• Peugeot Boxer Diesel

• Citroën Jumper

• Fiat Ducato Diesel

• Iveco Daily

• Renault Master

• Opel Movano

This list is not exhaustive.

The exact reductant temperature sensor location and configuration vary between manufacturers. On some vehicles, the sensor is located inside the DEF/AdBlue tank module, while on others it may be integrated into a larger reductant-system assembly.

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How Is P2046 Diagnosed?

P2046 should be diagnosed as an intermittent electrical sensor-circuit fault.

The most important objective is to determine why the temperature signal is becoming unstable.

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Step 1: Scan for Additional Trouble Codes

Use a suitable diagnostic scan tool to retrieve all stored, pending, and manufacturer-specific codes.

Look for related faults involving:

• Reductant temperature

• DEF/AdBlue

• Reductant heater

• Reductant level

• Reductant pressure

• Reductant pump

• NOx sensors

• SCR efficiency

• Aftertreatment communication

Related codes can provide important clues.

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Step 2: Check Freeze-Frame Data

Review the conditions under which P2046 was recorded.

Useful information includes:

• Engine RPM

• Vehicle speed

• Coolant temperature

• Ambient temperature

• Reductant temperature

• Battery voltage

• Reductant level

• Reductant pressure

• Heater command

• Vehicle operating time

If the code repeatedly occurs at a particular temperature or during vibration/load changes, this can help identify the cause.

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Step 3: Monitor Live Reductant Temperature

Use the scan tool to monitor the reductant temperature PID.

Watch for:

• Sudden jumps

• Sudden drops

• Implausible temperatures

• Signal dropout

• Temperature values that do not match ambient conditions

A temperature reading that changes dramatically without a physical reason is a strong indication of a sensor or circuit problem.

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Step 4: Inspect the Sensor and Connector

Locate the reductant temperature sensor or tank module.

Inspect:

• Connector

• Wiring

• Terminals

• Seals

• Sensor body

• Tank-module connections

Look for signs of moisture, corrosion, physical damage, or DEF contamination.

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Step 5: Perform a Visual Harness Inspection

Follow the harness from the reductant tank toward the control module.

Look for:

• Chafed insulation

• Melted wires

• Broken conductors

• Loose clips

• Poor routing

• Pinched wires

• Heat damage

Pay particular attention to areas where the harness moves or contacts the vehicle body.

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Step 6: Perform a Wiggle Test

An intermittent fault may disappear when the vehicle is stationary.

With the circuit monitored using a scan tool or appropriate electrical test equipment, carefully move the harness and connectors.

If the temperature signal changes while the harness is moved, the problem may be:

• Broken conductor

• Loose terminal

• Poor connector

• Internal harness damage

This is one of the most useful tests for P2046.

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Step 7: Check Reference Voltage

If the sensor uses a reference-voltage circuit, verify that the reference voltage is stable.

A fluctuating reference voltage can cause an unstable temperature signal.

Compare the measurement with manufacturer specifications.

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Step 8: Check Sensor Ground

Verify that the sensor ground is secure and has low resistance.

A voltage-drop test can help identify a poor ground connection.

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Step 9: Check Sensor Signal

Measure the sensor signal according to the manufacturer's diagnostic procedure.

Compare the signal with:

• Reductant temperature

• Manufacturer voltage specifications

• Expected thermistor characteristics

The signal should change smoothly as the actual temperature changes.

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Step 10: Check Sensor Resistance

If the manufacturer provides a resistance-versus-temperature specification, measure the sensor resistance.

For an NTC thermistor, resistance should generally change predictably with temperature.

Possible problems include:

• Infinite resistance

• Intermittent open circuit

• Very low resistance

• Sudden resistance jumps

• Resistance outside the specified range

Do not use a generic resistance value because different sensor designs have different characteristics.

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Step 11: Compare Sensor Temperature With Actual Temperature

When practical, compare the scan-tool temperature reading with the actual temperature of the reductant system.

The reading should be physically plausible.

For example, a vehicle sitting overnight in cold weather should not immediately report a reductant temperature dramatically higher than the surrounding environment without a valid reason.

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Step 12: Check Reductant Heater Operation

If the vehicle uses a reductant heater, verify that the heater operates correctly.

Monitor:

• Heater command

• Heater current

• Reductant temperature

• Battery voltage

A problem in a shared power or ground circuit can sometimes affect both heater and temperature-sensor operation.

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Step 13: Check for Shared Circuit Problems

Determine whether the temperature sensor shares circuits with other components.

A fault in a common:

• Power supply

• Ground

• Reference voltage

• Harness section

• Connector

can cause multiple aftertreatment faults.

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Step 14: Check Control-Module Wiring

Verify continuity between the sensor/tank module and the relevant control module.

Check for:

• Open circuits

• High resistance

• Short to ground

• Short to battery

• Short to another circuit

Perform testing according to manufacturer procedures.

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Step 15: Check the Tank Module

If the temperature sensor is integrated into the DEF/AdBlue tank module, test the module according to manufacturer specifications.

Some systems do not allow the temperature sensor to be replaced independently.

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Step 16: Check Manufacturer Technical Information

Search for manufacturer-specific:

• Technical Service Bulletins

• Wiring updates

• Connector repairs

• Tank-module issues

• Software updates

• Known reductant sensor faults

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Step 17: Clear the Code and Verify the Repair

After repairing the fault:

1. Clear P2046.

2. Start the vehicle.

3. Monitor reductant temperature.

4. Monitor the sensor signal.

5. Operate the vehicle under different temperatures and vibration conditions.

6. Verify reductant heater operation if applicable.

7. Test-drive the vehicle.

8. Rescan for stored and pending codes.

Because P2046 is intermittent, the vehicle should be tested long enough to confirm that the signal remains stable.

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How to Fix P2046

The correct repair depends on the cause of the intermittent signal.

Repair Damaged Wiring

Repair or replace:

• Broken wires

• Chafed wires

• Melted insulation

• Corroded conductors

• Damaged harness sections

Route and secure the harness correctly after repair.

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Repair or Replace the Connector

Replace damaged:

• Connector housings

• Terminals

• Seals

• Locking mechanisms

Clean corrosion only when the manufacturer permits it and when the terminals remain serviceable.

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Repair a Poor Ground

Repair:

• Corroded grounds

• Loose terminals

• Damaged ground wires

• High-resistance connections

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Repair the Reference-Voltage Circuit

If the sensor reference voltage is unstable, repair the associated circuit.

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Replace the Reductant Temperature Sensor

If testing confirms an internal sensor fault, replace the sensor when it is separately serviceable.

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Replace the Reductant Tank Module

If the temperature sensor is integrated into the DEF/AdBlue tank module and cannot be replaced separately, the applicable tank module or assembly may need to be replaced.

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Repair the Reductant Heater Circuit

If testing reveals a shared heater or power-supply problem, repair the heater circuit.

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Repair the Control Circuit

Repair any:

• Open circuit

• Short circuit

• High-resistance connection

• Damaged control wire

between the sensor and control module.

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Repair or Replace the Control Module

If the sensor and external wiring are proven good but the control module is not processing the signal correctly, the relevant ECM/PCM or aftertreatment control module may require repair or replacement.

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Update Control Module Software

If a manufacturer software update addresses an intermittent reductant-temperature fault, reprogram the applicable module.

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Perform Required Calibration

After replacing a reductant tank module, sensor, or control module, the vehicle may require:

• DEF system initialization

• Reductant level reset

• Temperature-sensor calibration

• Tank-module programming

• SCR system reset

• Aftertreatment self-test

The exact procedure varies by manufacturer.

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What Happens If P2046 Is Ignored?

Because the reductant temperature signal is unreliable, the SCR system may not have accurate information about the condition of the DEF/AdBlue.

Possible consequences include:

• DEF/AdBlue warnings

• Incorrect heater operation

• SCR dosing problems

• Increased NOx emissions

• Reduced SCR efficiency

• Additional aftertreatment fault codes

• Reduced engine power

• Speed limitations

• Potential restart restrictions on some vehicles

An intermittent code can become a permanent fault as wiring or sensor deterioration progresses.

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Can You Drive With P2046?

The vehicle may continue to drive normally with an intermittent P2046, but the fault should not be ignored.

Because the problem concerns the reductant temperature sensor circuit, the engine may initially show little or no change in performance.

However, if the fault becomes permanent, the vehicle may develop:

• DEF/AdBlue warnings

• SCR system warnings

• Reduced power

• Emissions-system faults

• Speed restrictions

If a DEF countdown or serious emissions-system warning appears, the vehicle should be diagnosed promptly.

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Is P2046 a Serious Code?

P2046 is generally considered a moderate-severity emissions-system fault.

The intermittent nature of the code means the vehicle may initially operate normally, but an unreliable reductant temperature signal can interfere with proper SCR operation.

The potential consequences include:

• Incorrect reductant heating

• Incorrect dosing strategy

• Increased NOx emissions

• Reduced SCR efficiency

• Additional aftertreatment faults

• Reduced engine power

• Operating restrictions

The seriousness therefore depends on whether the fault remains occasional or develops into a persistent sensor-circuit failure.

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P2044 vs. P2045 vs. P2046

These codes belong to the same general reductant temperature-sensor circuit family but describe different electrical conditions.

Code	General Meaning
P2044	Reductant Temperature Sensor Circuit Low
P2045	Reductant Temperature Sensor Circuit High
P2046	Reductant Temperature Sensor Circuit Intermittent

P2044 — Circuit Low

The control module detects a sensor signal below the expected range.

Possible causes include:

• Short to ground

• Low reference voltage

• Faulty sensor

• Wiring problem

P2045 — Circuit High

The control module detects a sensor signal above the expected range.

Possible causes include:

• Open circuit

• High resistance

• Missing ground

• Faulty sensor

• Wiring problem

P2046 — Circuit Intermittent

The sensor signal becomes unstable or temporarily disappears.

Possible causes include:

• Loose connector

• Broken conductor

• Chafed wiring

• Corroded terminal

• Internal sensor fault

• Intermittent power or ground

The sequence can therefore be remembered as:

• P2044 → Low

• P2045 → High

• P2046 → Intermittent

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P2046 vs. P2047, P2048 and P2049

The next codes move from the reductant temperature sensor to the reductant injection valve circuit.

Code	General Meaning
P2046	Reductant Temperature Sensor Circuit Intermittent
P2047	Reductant Injection Valve Circuit/Open Bank 1 Unit 1
P2048	Reductant Injection Valve Circuit Low Bank 1 Unit 1
P2049	Reductant Injection Valve Circuit High Bank 1 Unit 1

The distinction is important:

• P2046 concerns the reductant temperature sensor circuit.

• P2047 concerns an open reductant injection-valve circuit.

• P2048 concerns a low reductant injection-valve circuit signal.

• P2049 concerns a high reductant injection-valve circuit signal.

Therefore, P2046 should not automatically lead to replacement of the DEF injector. The diagnostic focus should initially be on the temperature sensor, tank module, wiring, connector, reference voltage, and ground circuit.

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How to Prevent P2046

Not every intermittent electrical fault can be prevented, but proper maintenance can reduce the risk.

Recommended practices include:

• Inspect DEF/AdBlue wiring during routine servicing.

• Repair damaged wiring promptly.

• Keep reductant-system connectors properly sealed.

• Protect harnesses from exhaust heat and abrasion.

• Avoid damaging the DEF tank or its wiring.

• Maintain the vehicle's battery and charging system.

• Use the correct DEF/AdBlue specification.

• Address DEF and emissions warnings promptly.

• Avoid unnecessary modifications to aftertreatment wiring.

• Follow manufacturer procedures after tank-module replacement.

• Inspect the system after repairs involving the DEF tank or exhaust system.

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Final Thoughts

P2046 Reductant Temperature Sensor Circuit Intermittent indicates that the vehicle's control system has detected an unstable or intermittently missing electrical signal from the reductant temperature sensor circuit.

The most common causes include:

• Loose connector

• Corroded terminals

• Damaged wiring

• Chafed harness

• Broken conductor

• Water intrusion

• Faulty reductant temperature sensor

• Faulty reductant tank module

• Poor ground

• Reference-voltage instability

• Shared circuit problems

• Control-module faults

• Software or calibration issues

The most important point is that P2046 does not automatically mean the DEF/AdBlue tank or temperature sensor must be replaced.

Because the code specifically identifies an intermittent circuit condition, the wiring and connectors deserve particular attention. A harness that works perfectly while stationary may fail when the vehicle vibrates or when the wiring moves.

The best diagnostic approach is to monitor the reductant temperature with a scan tool while performing a careful harness and connector inspection. A wiggle test, voltage-drop test, reference-voltage check, ground check, and sensor resistance test can help identify faults that a basic visual inspection may miss.

If the temperature sensor is integrated into the reductant tank module, replacement of the entire module may be necessary only after testing confirms that the integrated sensor or internal circuit is defective.

Ignoring P2046 can eventually lead to DEF/AdBlue warnings, incorrect reductant heating or dosing, reduced SCR efficiency, increased NOx emissions, additional aftertreatment codes, reduced engine power, and operating restrictions.

The correct repair is to locate the source of the intermittent signal, repair the wiring or connector or replace the confirmed defective sensor/module, perform any required calibration, clear the code, and verify that the reductant temperature signal remains stable under real operating conditions.