What causes GM code 41?

Failed ignition module Open or shorted bypass or EST wiring Poor module ground On some models an incorrect MEM CAL module sets this code

How do I fix GM code 41?

Check for spark at the plugs to confirm the failure Inspect module connectors for heat damage and corrosion Test bypass and EST circuits per the service manual Verify correct MEM CAL installation on serviced ECMs Replace the module only after wiring and grounds test good

41 Ignition Control Error

Q: What does GM code 41 mean?

GM code 41 — Ignition Control Error. Applies to 1986-1995 GM cars and C/K trucks, Camaro, Corvette.

Make: GM (1982-1995)
Category: Powertrain - Ignition
Severity: Check Engine Light
Applies to: 1986-1995 GM cars and C/K trucks, Camaro, Corvette

How to read it

Code 41 reads as 4 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 41 mean?

41 — Ignition Control Error. This code sets when your vehicle computer detects ignition control error.

Common causes of 41

Failed ignition module
Open or shorted bypass or EST wiring
Poor module ground
On some models an incorrect MEM CAL module sets this code

How to fix 41

Check for spark at the plugs to confirm the failure
Inspect module connectors for heat damage and corrosion
Test bypass and EST circuits per the service manual
Verify correct MEM CAL installation on serviced ECMs
Replace the module only after wiring and grounds test good