P0629Fuel Pump A Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- What 'fuel pump A control circuit' means differs by maker: at GM petrol engines it is the control line from the engine module to the fuel pump relay (high-side driver), at GM's LML diesel the lift pump, at Ford petrol engines with a pump driver module the secondary circuit from that module to the pump (reported as a duty cycle on a monitor line), and at Ford's 6.7 L diesel (F-650/750) the high or low side of the pump relay. P0629 means a short to battery voltage: GM detects voltage at the output while the driver is off (8 of 10 samples at 250 ms, two trips in 2018); because the driver hardware cannot always separate open circuit and short to voltage, P0627 may set as well. Ford's 6.7 L diesel reports a short to voltage on the high side of the pump relay within 0.2 s. If the pump can no longer be switched off it may keep running after switch-off and drain the battery.
- What you may notice
- Pump runs constantly or after switch-off
- Battery drained
- Possibly no start
- Check engine light on
- Likely causes
- LikelyControl wire shorted to a battery feed
- PossibleRelay contacts welded or relay faulty internally
- RareMoisture in the relay or fuse box
- RareDriver in the engine module shorted
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.