Malfunction Indicator Lamp Control Circuit Malfunction
A fault in the wiring or control circuit between the ECU and the malfunction indicator lamp (MIL). The MIL may stay on permanently, fail to light at key-on, or flicker — the OBD-II self-check on the bulb itself failed.
Affected components
- Mil lamp
- Mil wiring
- Instrument cluster
Common causes
- Medium likelihood: MIL bulb burnt out (older clusters)
- Medium likelihood: Instrument cluster MIL driver failed
- Low likelihood: Wiring fault between ECU and cluster
Possible symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Diagnostic notes
- The malfunction indicator lamp may illuminate
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.