What causes GM code 55?

Internal ECM analog to digital converter fault Poor ECM power or ground connection Voltage spike damage from charging system faults On digital EGR models a solenoid 3 fault uses this same code

How do I fix GM code 55?

Check ECM powers and grounds including fusible links Verify charging voltage is not spiking before condemning the ECM Inspect the ECM connectors for corrosion and backed out pins On digital EGR models test the EGR solenoid 3 circuit as the alternate cause Replace the ECM with the correct service number and transfer the PROM and CALPAK

55 ECM Error

Q: What does GM code 55 mean?

GM code 55 — ECM 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 55 reads as 5 flashes, pause, 5 flashes 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 55 mean?

55 — ECM Error. This code sets when your vehicle computer detects ecm error.

Common causes of 55

Internal ECM analog to digital converter fault
Poor ECM power or ground connection
Voltage spike damage from charging system faults
On digital EGR models a solenoid 3 fault uses this same code

How to fix 55

Check ECM powers and grounds including fusible links
Verify charging voltage is not spiking before condemning the ECM
Inspect the ECM connectors for corrosion and backed out pins
On digital EGR models test the EGR solenoid 3 circuit as the alternate cause
Replace the ECM with the correct service number and transfer the PROM and CALPAK