What causes GM code 48?

Worn spark plugs or plug wires Failed ignition coil or module Vacuum leak or lean mixture causing misfire Low compression on one or more cylinders

How do I fix GM code 48?

Read the code with a scan tool and note which cylinder is flagged if shown Inspect plugs wires and coils before replacing parts Check fuel pressure and intake for leaks Run a compression test if ignition and fuel test good Clear the code and road test to confirm the misfire is gone

48 Misfire Diagnosis

Q: What does GM code 48 mean?

GM code 48 — Misfire Diagnosis. Applies to 1992-1995 GM cars with enhanced misfire detection, Corvette, Camaro.

Make: GM (1982-1995)
Category: Powertrain - Ignition
Severity: Check Engine Light
Applies to: 1992-1995 GM cars with enhanced misfire detection, Corvette, Camaro

How to read it

Code 48 reads as 4 flashes, pause, 8 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 48 mean?

48 — Misfire Diagnosis. This code sets when your vehicle computer detects misfire diagnosis.

Common causes of 48

Worn spark plugs or plug wires
Failed ignition coil or module
Vacuum leak or lean mixture causing misfire
Low compression on one or more cylinders

How to fix 48

Read the code with a scan tool and note which cylinder is flagged if shown
Inspect plugs wires and coils before replacing parts
Check fuel pressure and intake for leaks
Run a compression test if ignition and fuel test good
Clear the code and road test to confirm the misfire is gone