Alternator field circuit low voltage.
P0625 — also written PO625, P 0625, 0625 — is the OBD-II code for generator field terminal circuit low. Same code, same fix: this page covers every spelling of it.
This code means your car's brain has lost control of the alternator's output, usually because of a snapped wire or a fried internal regulator. It’s a common headache on Fords and Transit vans with the 'Smart Charge' system.
P0625 is a electrical fault code, typically costing £150–£700 to put right in a UK garage.
What P0625 actually feels like to drive
- The battery light flickers on the dash, especially when you turn the heated screen or seats on.
- Headlights look a bit 'dim' when idling at the lights, then brighten up when you rev it.
- Stop/Start system stops working entirely (the car 'decides' it hasn't got the juice).
- The steering feels heavy or 'notchy' on cars with electric power steering (EPS).
- A strange 'whining' noise from the engine bay that rises and falls with engine speed.
What causes P0625?
- Wiring fault
- Failed alternator regulator
UK vehicles that throw P0625 most often
- Ford Focus 1.6 TDCi (2008-2015) - Very common loom breaks.
- Vauxhall Insignia 2.0 CDTi (A20DTH) - Regulator failure.
- Ford Transit Custom 2.2 TDCi (2012-2018) - Corroded connector pins.
- BMW 3 Series (E90/E92) - Lin-bus communication errors.
- Mini Cooper (R56) - Oil wicking into the alternator harness.
- Volvo V40 2.0 D2 - Smart charging circuit faults.
How P0625 is fixed
- Test wiring
- Replace alternator
The P0625 misdiagnosis that wastes money
I’ve seen dozens of lads rush to fit a cheap eBay alternator as soon as P0625 pops up, only to find the battery light stays on. On modern Ford and Vauxhall systems, the actual fault is usually a tiny break in the LIN-bus or PWM control wire, often right at the connector plug where it vibrates against the casing. They swap the unit, charge the customer £300, and the car comes back two days later flat as a pancake. Always check the signal wire for continuity before condemning the 'genny'.
What a UK garage should charge for P0625
A diagnostic plug-in and loom test will run you £60–£100 at an independent. If it’s just a broken wire repair, you're looking at £120 all-in. If the alternator is toast, a decent Bosch or Lucas unit costs £180–£350, plus 2 hours labour (£120–£200 depending on the car’s layout). Total bill usually lands between £350 and £550. Main dealers like Arnold Clark will easily quote you £800+ for the same job using 'Genuine' branded parts.
P0625 repair cost in the UK
Most P0625 repairs land between £150–£700 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0625
If you’re taking this to a garage, ask them specifically if they've checked the 'duty cycle' of the alternator with an oscilloscope or a high-end scan tool. If they just say "it's not charging," they might be guessing. On Fords, insist they check the 'Smart Charge' loom for corrosion. A proper diagnostic should cost you about £60 to £90. If it does need a new unit, ask for a Bosch or Denso exchange unit — avoid the unbranded 'white box' specials unless you want to be doing the job again in six months for the MOT.
Can you drive with P0625?
Yes short-term.
Urgency: medium.