P2501
Generator Lamp/L-Terminal Circuit High
The L-terminal feedback from the alternator reads above the upper limit — short to supply or open ground side. Charging diagnostics cannot run cleanly.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- L-terminal shorted to supplyCommon
- Alternator regulator failedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Alternator
- Charging Warning Lamp Wiring
P2501 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.