P0648Immobilizer Lamp Control Circuit
- Generic OBD-II code · Powertrain
- How the car detects it
- The engine module switches this hard-wired output with its own driver and checks the circuit electrically (open, short to ground or voltage) – it cannot see whether the lamp lights; on CAN-based cars such faults appear as U codes. P0648 concerns the immobiliser or security lamp where the engine module drives it directly by wire – on GM and Saab systems this lamp shows the immobiliser learn mode and faults. No manufacturer document available to us uses this code; the description follows CARB and the component. The lamp then does not show the immobiliser status, or shows it permanently; the immobiliser itself keeps working, because start authorisation is separate (key faults are P0513/P0633). The immobiliser is not an emission component, so no check engine light is expected.
- What you may notice
- Immobiliser lamp off, permanently on or flashing wrongly
- Code stored
- Engine start normally not affected
- Likely causes
- LikelyWire or connector between module and receiver open, corroded or shorted
- PossibleBulb/LED or instrument cluster faulty
- PossibleInstrument cluster (board, connector) faulty
- RareOutput driver in the module faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.