What it means
Same as P04CE with the signal in plausible range yet not matching the engine model - typically sensor drift or a slow response after engine warm-up.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR temperature sensor C reports exhaust gas recirculation temperature so the control module can assess EGR operation. P04CF sets when the signal is electrically plausible but does not track the temperature the module expects, such as when sensor C drifts or responds too slowly.
Common causes
Most likely first.
- EGR temperature sensor drifting or responding slowly
- Loose or corroded connector
- Damaged sensor wiring
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
How to diagnose it
- Review freeze-frame data and compare sensor C live readings with engine temperature and EGR operating conditions.
- Inspect sensor C and its connector for looseness, corrosion, contamination, or heat damage that could slow or distort the reading.
- Check the sensor C wiring for damage and verify continuity and connections against the manufacturer's specification.
- Observe whether sensor C changes smoothly as the engine and EGR system warm; compare its response with other temperature data where available.
- Test or replace sensor C only after confirming the signal wiring and operating conditions are sound.
Common fixes
- Repair a loose, corroded, or heat-damaged sensor C connection.
- Repair damaged sensor wiring that distorts or delays the signal.
- Replace EGR temperature sensor C if its reading drifts or responds slowly during testing.
- Address a verified EGR operating fault if it is causing the temperature reading to fall outside the expected pattern.
Can I keep driving?
With a steady warning light and normal running, limited gentle driving may be possible, but avoid heavy load if the engine knocks or hesitates and have the cause checked soon. Poor EGR feedback can increase NOx emissions and contribute to rough running or power loss.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.