What it means
Fuel Pump A Control Circuit High: the control-circuit voltage is above the expected range. Often an open circuit or a short to supply voltage.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Fuel Pump A's control circuit switches or regulates power to the pump under ECM command. P0629 is set when the monitored control-circuit voltage is higher than expected, which can happen with an open ground path or a short to supply voltage and may prevent the pump from responding correctly.
Common causes
Most likely first.
- Pump circuit shorted to power
- Ground open
- Connector pins corroded - high contact resistance
Symptoms
- Engine may crank but fail to start
- Engine may stall or lose power if fuel delivery is interrupted
How to diagnose it
- Record freeze-frame data and check fuel pressure and related pump codes to see whether the high signal occurred with a starting or stalling problem.
- Inspect Fuel Pump A's relay, connector, harness, and ground points for loose terminals, corrosion, broken ground wiring, or insulation damage.
- Check for unintended voltage on the control wire when the pump is not commanded on.
- Compare commanded pump state with circuit voltage during prime and operation using live data and a meter.
- Test the circuit for an open ground and short to power, then verify relay and pump operation against the manufacturer's specification.
Common fixes
- Secure or clean loose Fuel Pump A connector and ground connections.
- Repair an open ground wire or corroded ground point.
- Repair wiring shorted to battery or another supply circuit.
- Replace a faulty relay or pump only if circuit tests identify it as the source of the high reading.
Can I keep driving?
If the engine cranks without starting, stalls, or loses power, avoid driving because fuel delivery may be unreliable. Arrange repair before a trip; an unexpected stall can leave you stranded or create a road hazard.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.