CODE 51 - PROM Fault
Trouble Code 51 indicates that the ECM sensed a fault in the PROM.
When the PROM was initially created, a checksum number representing the total of all the cell values was also stored. The ECM uses this checksum as one way to determine if the contents of any cell has changed. A Code 51 causes the ECM to enter Back-Up mode which uses the CALPAK for default sensor values.
The conditions for setting this code are:
- or -
Typical causes for this code include:
1) Incorrectly installed PROM module
2) Defective PROM module
3) Defective ECM