What causes GM code 51?

Loose or corroded PROM or MEM CAL in the ECM socket Incorrect MEM CAL for the vehicle Bent PROM pins from prior service Failing ECM socket or internal fault

How do I fix GM code 51?

Turn the key off and reseat the PROM or MEM CAL carefully Inspect pins for bends and corrosion and clean contacts Verify the MEM CAL part number matches the vehicle calibration Clear codes by disconnecting battery power and recheck Replace the MEM CAL or ECM only after seating and part number check good

51 PROM Error

Q: What does GM code 51 mean?

GM code 51 — PROM Error. Applies to 1982-1995 GM cars and C/K trucks, Camaro, Corvette.

Make: GM (1982-1995)
Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: 1982-1995 GM cars and C/K trucks, Camaro, Corvette

How to read it

Code 51 reads as 5 flashes, pause, 1 flash on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

What does GM code 51 mean?

51 — PROM Error. This code sets when your vehicle computer detects prom error.

Common causes of 51

Loose or corroded PROM or MEM CAL in the ECM socket
Incorrect MEM CAL for the vehicle
Bent PROM pins from prior service
Failing ECM socket or internal fault

How to fix 51

Turn the key off and reseat the PROM or MEM CAL carefully
Inspect pins for bends and corrosion and clean contacts
Verify the MEM CAL part number matches the vehicle calibration
Clear codes by disconnecting battery power and recheck
Replace the MEM CAL or ECM only after seating and part number check good