P0627
PowertrainFuel Pump A Control Circuit /Open
The fuel pump control circuit is what lets the ECU switch the pump on and tell it how hard to work. P0627 means that circuit has gone open, so the signal isn't getting through. Depending on the car that can mean a pump running flat out, not running at all, or running when it shouldn't. The end result is fuelling problems, anything from a hard start on a cold morning to a car that won't fire up on your driveway.
ⓘ Information only. This page provides general educational information about fault code P0627. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0627 mean?
P0627 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Fuel Pump A Control Circuit /Open.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on the dash, sometimes the first thing you notice before any running issue
- • Long cranking before it catches, worst when the engine is stone cold
- • Stalling or cutting out while you're driving, often with no warning
- • Flat spots and hesitation when you put your foot down
- • Down on power generally, and on some setups the car drops into limp mode
- • Some vehicles simply won't start at all, and you'll get a no-start with the warning light
Possible causes
Causes commonly associated with P0627, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Damaged or corroded wiring between the pump and the control module, or a connector that's worked loose. This is the bread and butter cause and where most P0627 jobs end up
- 2. Faulty fuel pump relay that's stopped switching cleanly, cheap to rule out and worth checking early
- 3. A failed fuel pump driver module, the bit of electronics that actually commands the pump. Common on cars that run a separate driver rather than a simple relay
- 4. The pump itself worn out and no longer responding to the control signal, more likely on higher mileage cars
- 5. Corroded or damaged connectors in the harness, often where moisture has tracked in over the years
- 6. Water ingress into a plug or earth point, which is why this one loves to show up after a spell of wet weather
- 7. A fault in the powertrain control module, rare and roughly the last thing to suspect, under 2% of cases in the draft figures
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the full code list, not just the P0627. If there are pressure codes like P0230 or P0087 sitting alongside it, that changes where you look first
- 2. Get under the back and physically check the pump wiring, connectors and any inline relay or driver module for green corrosion, chafed insulation or a plug that isn't seated
- 3. Back-probe the relay and check it switches with the ignition on, and confirm continuity through the contacts with a multimeter
- 4. Check you've got proper voltage and a clean earth at the pump connector when the key is turned. No supply points you back up the harness toward the driver or relay
- 5. Look closely at the driver module for heat marks, swollen casing or burnt pins, since these cook themselves and fail open
- 6. Fix one thing at a time, clear the code, then drive it. That tells you which repair actually sorted it rather than guessing
Common questions about P0627
Will my car fail its MOT with a P0627 stored? +
The stored code on its own isn't a tester's concern, but if the engine warning light is lit when the car goes on the ramp, that's an MOT fail on the dashboard warning light check. So if you've fixed the cause, drive it long enough to clear the light before the test. If the fault is still live and the pump is misbehaving, you've got bigger problems than the MOT anyway, because a stalling or non-starting car won't get far enough to be tested.
What's this likely to cost me to put right? +
It swings a lot depending on what's actually broken. A new fuel pump relay is a low two-figure part and often under an hour's labour at an independent. Tracing and repairing a corroded section of wiring usually lands in the low hundreds once diagnostic time is added. A full pump replacement is the dear option, commonly mid to high three figures, and can tip over £1,000 at a main dealer once you factor in their hourly rate. An independent garage will almost always beat the franchised price, especially on the diagnostic hours.
How do I work out which of these it actually is on my car? +
Start with the cheap and obvious. Try the relay first, either swap it for an identical one elsewhere in the box or test it with a meter, because if that's the fault you've solved it for pennies. If the relay's fine, check whether the pump is getting voltage and a good earth at its plug with the ignition on. Power present but no pump points at the pump or its driver module. No power present means the open is back in the wiring or the driver itself. If the code comes and goes with wet weather or over bumps, you're chasing a corroded connector or a damp earth rather than a dead component, so wiggle-test the plugs while watching live data.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →