P0626 — Generator Field Terminal Circuit High
Seen on: Heavy Truck
Generator Field Terminal Circuit High. Common causes: Alternator field circuit open.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Alternator field circuit open
- Open field wire
- failed regulator
First moves (roadside)
- Test field wire continuity
- replace alternator or regulator
FAQ
Generator Field Terminal Circuit High. Common causes: Alternator field circuit open.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Alternator field circuit open. Other possibilities include Open field wire; failed regulator.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.