P0627: Fuel pump "A" control circuit/open
The engine computer has found a fault in the fuel pump’s control circuit: open, or a voltage too low or too high. The pump may not run properly, so the engine can stall or not start.
Updated
What P0627 means
The engine computer switches the fuel pump in the tank, through a relay or, on many newer cars, a fuel pump control module that also sets the pump’s speed. On many diesels this is the lift pump that feeds the high-pressure pump.
P0627 means the engine computer has found an open circuit in that control. If the pump stops, the engine stops.
P0628 and P0629: control circuit low or high
P0628 means the voltage in the pump’s control circuit is too low, for example from a short to earth, and P0629 that it’s too high, for example from a short to a supply wire. The risk and the checks are the same.
P0628: Fuel Pump A Control Circuit Low
P0629: Fuel Pump A Control Circuit High
Can I keep driving?
Drive gently
Drive gently and only as far as you need to, and have it checked soon. The engine can cut out without warning and may not restart; steering and braking then get much heavier. Avoid motorways and long trips until it’s fixed.
General guidance based on the code alone, not on the car’s actual condition. If in doubt, stop and ask a mechanic.
A pump that stops while driving cuts the engine out, usually without warning, and it may not restart until the fault clears.
Symptoms
- The engine cranks but doesn’t start, or takes a long time to start.
- The engine stalls while driving, and may restart after a while.
- On some cars, loss of power or hesitation when accelerating.
Common causes
- Faulty fuel pump relay or fuel pump control module. A common cause, and cheaper to check than the pump itself.
- Wiring or connector fault, often near the fuel tank. The wiring to the pump runs under the car to the top of the tank, where corrosion and chafing are common.
- Faulty fuel pump. A pump with a broken winding sets the same code.
Typical fixes
- Check the fuel pump fuse and relay.
- Check the connector on top of the fuel tank and the wiring to it for corrosion and damage.
- Have the fuel pressure measured while cranking, and the pump’s control signal checked.
- Replace the fuel pump control module or the pump if the wiring is fine.
Questions
Can I drive with P0627?
Gently, and only as far as you need to: the engine can cut out without warning and may not restart, and steering and braking then get much heavier. Avoid motorways and long trips, and have it checked soon.
Does P0627 mean the fuel pump is broken?
Not necessarily. The code is about the pump’s control circuit: a fuse, a relay, a connector or the control module are just as likely. Have the circuit checked before replacing the pump.