P0625: Generator Field/F Terminal Circuit Low

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. P0625 means the F feedback is too low: with the engine running the regulator reports (almost) no field duty cycle – typically an open or grounded F line, or the alternator is not charging. The Saab 9-4X sets it below 3000 rpm when the duty cycle stays under 5 % for 15 s; Saab's T8 when it stays under 0.5 % for over 30 s with the L line active, and raises the idle speed. Ford's 6.8 L V10 reports it with or without the check engine light depending on the variant. GM's newer engines combine low and high in P0622.

Medium severity. Can I keep driving?If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.

Symptoms

Battery warning lamp on
Battery not or incorrectly charged, starting problems
Raised or fluctuating idle
Check engine light on some Ford variants

Most likely causes

F line open or shorted to ground, connector corroded
Regulator or alternator faulty or not charging (brushes, field winding)
Alternator B+ feed missing or high resistance
Engine module

What to check, in order

Start with the simplest. You can tick off each step.

Measure the voltage with the engine off and running
With the connector unplugged, check whether the signal wire is making contact with ground.
Clean and tighten the terminals
Check the accessory belt
Run a battery load test
Check the alternator wiring

Good to know

Repair difficulty: medium

What each character of P0625 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
6: Control modules and outputs
25: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0625?

If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.

What causes code P0625?

The most common causes are: f line open or shorted to ground, connector corroded; regulator or alternator faulty or not charging (brushes, field winding); alternator B+ feed missing or high resistance.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.