P0629 code meaning
Fuel Pump A Control Circuit High
Powertrain system Generic code P06xx codes Check engine light
What P0629 means
What 'fuel pump A control circuit' means differs by maker: at GM gasoline 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 gasoline 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.
P0629 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P0629
- Pump runs constantly or after switch-off
- Battery drained
- Possibly no start
- Check engine light on
Common causes of P0629
- Most likelyControl wire shorted to a battery feed
- PossibleRelay contacts welded or relay faulty internally
- Less likelyMoisture in the relay or fuse box
- Less likelyDriver in the engine module shorted
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel pump relayFuel pump driver moduleFuel pumpEngine control module
What each part of P0629 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| 29 | The exact fault in that area. |
What to do next
- Note P0629 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0629
What does P0629 mean?
P0629 means "Fuel Pump A Control Circuit High". What 'fuel pump A control circuit' means differs by maker: at GM gasoline 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 gasoline 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0629?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0629 fail an emissions test?
Yes, it can. P0629 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0629 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0629 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.