P040B
PPowertrainEGR Temperature Sensor A Range/Performance
What does this code mean?
Severity : MediumP040B means the signal from EGR temperature sensor "A" is out of the expected range or does not match engine operation. This sensor measures the temperature of the recirculated exhaust gas. The ECU compares it with other sensors and with EGR valve opening to check that it makes sense.
Symptoms
- Check engine light on.
- Often no noticeable driving symptom.
- Slight loss of power or rough idle.
- Possible increase in emissions.
Possible causes
- EGR temperature sensor fouled with soot or faulty.
- Corroded or damaged connector or wiring.
- Sticking EGR valve changing gas temperature.
- Clogged or failing EGR cooler.
- Faulty engine control module, less commonly.
Diagnosis and repair
- Compare EGR temperature with other engine temperatures on a cold engine in live data.
- Inspect the sensor connector and wiring.
- Measure sensor resistance at different temperatures.
- Check operation of the EGR valve and cooler.
- Replace the sensor if needed, then clear the code and road test.
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Code
P040B
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012