For 1990-2009 cars

DTC | DTC Parameters | Diagnosis
--- | --- | ---
P0601 PCM memory | This DTC will set when the PCM determines that the PCM RAM memory is faulty. | Record all PCM DTCs and include with repair information. Replace and reprogram the new PCM.
P0602 PCM not programmed | This DTC will set if the PCM is not programmed correctly. | Record all PCM DTCs and include with repair information. Reprogram the PCM and if this fault returns replace and reprogram the new PCM.
P0603 PCM long-term memory reset | This DTC will set when the PCM non-volatile random access memory fails. | Record all PCM DTCs and include with repair information. Reprogram the PCM and if this fault returns replace and reprogram the new PCM.
P0606 PCM internal performance | This DTC will set when the PCM determines that its microprocessor has failed. | Record all PCM DTCs and include with repair information. Replace and reprogram the new PCM.