P0623Generator Lamp Control Circuit
- Generic OBD-II code · Powertrain
- How the car detects it
- P0623 concerns the control of the battery warning lamp by a module's output driver, not the alternator itself. Traditionally the regulator switches the lamp through terminal L; where a module switches it instead – GM's Saab 9-4X turns the lamp on 15 s after a charging code – it can monitor its lamp output for open or short circuits. No manufacturer document available to us uses P0623, so the description follows the principle of other lamp outputs. Under CARB a pure indicator lamp needs the check engine light only if other diagnostics depend on it, which is rarely the case. The lamp then never lights (not even at the bulb check) or stays on, and real charging faults may go unnoticed. The L line itself is P0621; the fuel cap lamp P0624 belongs to a different system.
- What you may notice
- Battery lamp never lights (not even at bulb check) or stays on
- Real charging faults may not be displayed
- Otherwise usually no driving symptoms
- Likely causes
- LikelyWire or connector to the lamp or instrument cluster
- PossibleBulb/LED or instrument cluster faulty
- RareOutput driver in the module
- RareGround fault
- Repair
- Medium · Usually a job for a workshop.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.