P0625
Generator Field Terminal Circuit Low
Voltage on the alternator F terminal (field excitation) is below threshold — open or short to ground in the excitation path.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Field circuit open or shorted to groundCommon
- Alternator brushes wornPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Alternator
- Alternator Wiring
P0625 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.