P040C
PPowertrainEGR Temperature Sensor A Circuit Low
What does this code mean?
Severity : MediumP040C indicates a low voltage on the EGR temperature sensor A circuit. This sensor measures the temperature of recirculated exhaust gas to confirm the EGR valve and cooler are working. A low voltage often means a short to ground or an abnormally high temperature reading.
Symptoms
- Check engine light on.
- EGR operation reduced or disabled.
- Possible slight loss of power.
- Higher NOx emissions.
Possible causes
- Faulty EGR temperature sensor.
- Signal wire shorted to ground.
- Heat-damaged wiring.
- Dirty or wet connector.
- Faulty control module, less often.
Diagnosis and repair
- Inspect the sensor connector and wiring, especially near the exhaust.
- Compare the sensor value with other temperatures on a cold engine.
- Measure sensor resistance with a multimeter and check for a short to ground.
- Replace the sensor or repair the wiring.
- Clear the code and road test.
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Code
P040C
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012