OBD-II Code · Powertrain
P0625
Generator Field Terminal Circuit Low
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$200–$700
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Alternator field terminal reading low — alternator may not be charging properly.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Battery light
- Dim lights at idle
- Battery dies
Likely causes
- Failed alternatorMost common
- Wiring
- Bad ground
Read the full diagnostic procedureP0625 indicates the generator field terminal (the F terminal that PCM-controlled alternators use to command field current via PWM) is reading lower t…
P0625 indicates the generator field terminal (the F terminal that PCM-controlled alternators use to command field current via PWM) is reading lower than expected, suggesting either a shorted-to-ground field driver, a failed regulator inside the alternator, or an open in the control wire from the PCM to the alternator.
Cheapest-first
- with the engine running, measure charging voltage at the battery — it should be 13.5-14.7V on a healthy system.
- If it is at or below battery voltage (12.0-12.4V), the alternator is not field-energized.
- Back-probe the F-terminal wire at the alternator and look for a PWM signal that varies with electrical load (turn on headlights and rear defroster — duty cycle should increase).
- No signal at the alternator means the PCM driver or wiring is at fault; signal present but no charging means the alternator's internal regulator is failed.
- Inspect the alternator connector for corrosion and burnt pins — a heavily loaded charging system at high temperatures cooks these connectors regularly.
- Verify battery voltage is 12.4V+ at rest before condemning the alternator, because a deeply discharged battery can pull the field driver into a fault condition that mimics P0625.
- The expensive misdiagnosis is replacing the alternator without checking the connector and wiring — install a new alternator into a corroded connector and the same code returns within days.
Vehicle-specific patterns2006-2013 GM trucks and SUVs (Silverado, Tahoe, Suburban) with PCM-controlled alternators commonly set P0625 from internal regulator failure in the A…
- 2006-2013GM trucks and SUVs (Silverado, Tahoe, Suburban) with PCM-controlled alternators commonly set P0625 from internal regulator failure in the AD244/AD230 alternator, documented in GM bulletin 09-06-03-005.
- 2005-2010Ford F-150 and Expedition with the 6G alternator throw P0625 from corroded 4-pin alternator connectors at the regulator, addressed by Ford TSB 10-22-1 with a pigtail repair kit.
- 2007-2014Chrysler/Dodge/Jeep with the dual-purpose regulator throw P0625 when the field circuit driver inside the PCM fails or when the alternator's internal voltage regulator shorts.
- 2005-2012VW/Audi with the load-response regulator set P0625 from broken field wires at the alternator's terminal block.
Estimated repair$80 to $900.
Look up another code
P0625 — frequently asked
What does a P0625 code mean?
Alternator field terminal reading low — alternator may not be charging properly.
What causes a P0625 code?
Common causes: Failed alternator; Wiring; Bad ground.
What are the symptoms of a P0625 code?
Typical symptoms: Battery light; Dim lights at idle; Battery dies.
Is it safe to drive with a P0625 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $200-$700.
How do I diagnose a P0625 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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