P0604

DTC P0604
Control unit defective (iRAM) Drive cycle A:Signal implausible.

Possible causes by suggested order of priority:
- Battery connections/condition.
- Severe environmental conditions.
- Faulty Motronic ECM.

Battery connections/condition.
- Check voltage 10.0 to 14.0 volts

Severe environmental conditions.
CHECK THE FOLLOWING:
- ECM has been operated at extremely high ambient temperature.
INFORMATION
- The ECM may temporarily fail if it's temperature rises to about 130°C.
- This would not normally be expected to happen even in ambient temperatures >40°C.

Faulty Motronic ECM.
CHECK THE FOLLOWING:
- Permanent supply fault flag is not set.
- Environmental condition 'battery voltage' logged as >6V when fault occurred.
- Clear fault and monitor for re-occurance.
POSSIBLE FAULTS
- Faulty Motronic ECM.