OBD codes / P0625
P0625
ModerateGenerator Field Terminal Circuit Low
An undercharging alternator drains the battery as you drive, and the car can die mid-trip once the battery is spent — often with electrical warnings stacking up first. Treat P0625 as a fix-soon code: test the charging system promptly and avoid long or remote drives until it's sorted.
What this code means
P0625 means the voltage on the alternator's field circuit — the winding that creates the magnetic field which lets the alternator generate power — is reading lower than the computer expects. Less field current means less charging output, so the real-world consequence is an undercharging system and a battery that slowly drains. The cause can be inside the alternator (worn brushes, a failing regulator, a shorted field winding) or outside it: a chafed or shorted field wire, a corroded connector at the alternator, or poor grounds. As with any charging code, start with the basics — battery terminals, ground straps, belt condition — and a charging-system output test, before replacing hardware.
Symptoms you might notice
- Battery or charging warning light
- Battery slowly draining or repeatedly going flat
- Dim headlights, especially at idle
- Low voltage reading on the dash gauge
- Check-engine light
What it costs to fix
Typical range: $20–$800 · about ~0.3–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Wiring / connector repair | $5–$100 | ~0.3–1.5 hrs |
| Alternator | $150–$500 | ~0.5–2 hrs |
On most modern cars the regulator and brushes are built into the alternator, so an internal fault means replacing the whole unit — the expensive path. A damaged field wire or corroded plug is the cheap path. Labor depends on alternator access, which varies widely by engine.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0625 for my exact vehicle →
Frequently asked
Can I drive with P0625?
Short trips while you arrange a charging-system test, yes — but if the alternator is undercharging, the battery is quietly draining and the car will eventually stall and refuse to restart. Don't push your luck on distance.
What is the alternator field circuit?
It's the winding that gets energized to create the magnetic field the alternator needs to generate electricity. The computer controls charging output by varying field current, so a low reading there means weak or no charging.
Is P0625 the alternator or the wiring?
Either. Worn brushes or a failing regulator inside the alternator can drag the field voltage low, but so can a damaged wire or corroded connector outside it. The wiring is the cheap possibility, so it gets tested first.
Why does my battery keep dying with this code?
A weak field means weak charging, so the car draws down the battery faster than the alternator refills it. Replacing the battery alone won't fix that — the new one will drain too until the charging fault is repaired.
Seeing P0625 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0625 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.