ECM and TCM Incompatible
The ECM and TCM exchange identification or calibration data over the powertrain bus and detect that they are not a valid pair - typically appears after replacing one of the modules with a unit from a different vehicle variant.
Affected components
- Ecm
- Tcm
Common causes
- High likelihood: Replacement part from wrong variant
Possible symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Diagnostic notes
- The malfunction indicator lamp may illuminate
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.