Damaged, chafed or heat-affected wiring shorting the signal wire to ground; Faulty EGR temperature sensor (internal short); Water, corrosion or contamination in the sensor connector or terminals; Sensor signal wire shorted to another ground or sensor return wire in the harness; Sensor reading genuinely very hot due to an EGR valve stuck open, a cooler fault or a heat-related problem (model dependent); Fault inside the engine control unit's sensor input circuit.

P041C

EGR Temperature Sensor B Circuit Low.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
4: AreaAuxiliary emission controls
1C: FaultThe specific fault in that area

What it means

P041C means the engine control unit has seen the signal from EGR temperature sensor 'B' fall below its expected range, usually a voltage close to zero. This points to a short to ground in the circuit or a faulty sensor. Which physical sensor is 'B' (for example before or after the EGR cooler, or on a second bank) depends on the engine, so check the model-specific wiring information.

Symptoms

Engine warning light on
Possible reduced or disabled EGR operation, with the control unit using a fallback strategy
Slightly rougher running or hesitation in some conditions
Higher emissions or a failed emissions test
Other EGR-related fault codes stored alongside it

Possible causes

Damaged, chafed or heat-affected wiring shorting the signal wire to groundlikely
Faulty EGR temperature sensor (internal short)likely
Water, corrosion or contamination in the sensor connector or terminalspossible
Sensor signal wire shorted to another ground or sensor return wire in the harnesspossible
Sensor reading genuinely very hot due to an EGR valve stuck open, a cooler fault or a heat-related problem (model dependent)possible
Fault inside the engine control unit's sensor input circuitrare

How to diagnose

Read all stored codes and freeze frame data, and note whether other EGR, intake or exhaust temperature codes are present.
Look at live data for EGR temperature sensor B on a cold engine and compare it with other temperature readings such as coolant and intake air; it should be similar.
Inspect the sensor, wiring and connector for chafing, heat damage, corrosion, moisture or bent terminals, especially near the exhaust.
With the ignition on, unplug the sensor and see whether the reading or voltage moves to the open-circuit value; if the fault stays, suspect the harness, if it clears, suspect the sensor.
Measure the sensor resistance and compare it with the manufacturer's figures at a known temperature.
Check the signal wire for a short to ground and for continuity to the control unit with the unit disconnected, following the wiring diagram.
Check the EGR valve and cooler operation for a fault that would cause real overheating, as the procedure depends on the model and engine.
Clear the code and road test, then recheck live data to confirm the fault does not return.

How to fix

Repair or replace the damaged wiring section and secure it away from hot or sharp parts.
Clean, dry and repair the connector, or replace it if terminals are corroded or damaged.
Replace the EGR temperature sensor if its resistance or response is out of specification.
Repair any short between the signal wire and ground or the sensor return in the harness.
Repair or replace the EGR valve or cooler if it is found to be causing genuine overheating.
Have the control unit tested, and repaired or replaced, only once wiring and sensor are proven good.

Can I keep driving?

Low severity

The car can normally be driven while you book it in, as the control unit will usually use a fallback strategy. Get it checked soon, as EGR operation may be limited and the car may fail an emissions test, and stop if driveability worsens noticeably.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.