EGR Temperature/Charge Air Cooler Temperature Correlation
After a long key-off soak both the EGR temperature sensor and the charge-air cooler outlet temperature sensor must read approximately the same ambient temperature. The ECM compares them and detects an implausible delta. One of the sensors drifts, is wired wrong, or is exposed to a heat source the model does not know about.
Affected components
- Egr temperature sensor
- Cac outlet temperature sensor
Common causes
- High likelihood: One sensor drifting outside tolerance
- Medium likelihood: Residual heat in the charge-air cooler after a hot soak
Possible symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.