51 PCM Memory Error
Each time the PCM is powered up, several terminal tests are performed on the random access memory (RAM), electronically programmable read only memory (EPROM) and electronically erasable/programmable read only memory (EEPROM). If there is a fault in one or more of these, Code 51 will set.
Code 51 will set if:
- The PCM memory is malfunctioning.
- Code 51 indicates an internal PCM/EC malfunction. The PCM should be replaced.
If you are hacking your PCM, and this code pops up, most likely you didn't set a checksum correctly. The RAM is checked with a simple write/read command, and the EEPROM and EPROM are checksumed and checked with what is stored.