P0620Generator Control Circuit
- Generic OBD-II code · Powertrain
- How the car detects it
- The alternator regulator is linked to the engine module by an L (turn-on) line, an F (field) line reporting field load as a duty cycle, or on newer cars a LIN bus. P0620 is the general control circuit code. On LIN alternators it stands for disturbed control or communication: a manufacturer table published via NHTSA (gateway module with LIN alternator) lists it with the battery lamp on and stop-start disabled, alongside P065B for range/performance. Saab's 9-3 diesel uses it for the L line – open between module and alternator for more than 6 s, or a charging signal in an implausible state. Ford's 6.8 L V10 reports it with or without the check engine light depending on the variant. GM does not use P0620 and reports L and F line faults as P0621/P0622.
- What you may notice
- Battery warning lamp on
- Battery not or incorrectly charged, starting problems
- Stop-start not working
- Sometimes no noticeable symptoms
- Likely causes
- LikelyConnector or wire between module and alternator (corrosion, break, chafing)
- LikelyAlternator or regulator faulty, including its LIN interface
- PossibleBattery flat or faulty, jump start or charger connected
- RareLoose or worn drive belt
- RareEngine module or gateway (software, driver)
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.