OBD codes / P0628
P0628
SeriousFuel Pump A Control Circuit Low
P0628 carries a real risk of stalling or a no-start, since the fault sits in the circuit that keeps the fuel pump running. Don't plan long or high-stakes trips on it — get the circuit tested promptly, and treat any new hesitation or hard-start as the warning it is.
What this code means
P0628 means the voltage on the fuel pump control circuit is stuck lower than the computer expects — commonly a control wire shorted to ground, a failed relay, a corroded connector, or a failing fuel pump driver module. Because this circuit is what switches and manages the pump, a real fault here can leave the pump underpowered or not running at all, and the engine responds with hard starting, stalling, or a no-start. On vehicles that vary pump speed electronically, a dragging control signal can also cause poor performance under load before it becomes a full failure. The relay and the visible wiring are the affordable first checks; the driver module and pump-side testing come next.
Symptoms you might notice
- Hard starting or long cranking
- Stalling, especially under load or at speed
- Engine cranks but won't start
- Hesitation or power loss under acceleration
- Check-engine light
What it costs to fix
Typical range: $20–$600 · about ~0.2–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Fuel pump relay | $15–$50 | ~0.2–0.5 hrs |
| Wiring / connector repair | $5–$100 | ~0.5–2 hrs |
| Fuel pump driver module (where fitted) | $100–$400 | ~0.5–1.5 hrs |
The relay is the cheap gamble, wiring repairs vary with the location of the short, and the driver module is the more expensive electronic culprit. If testing shows the pump itself is failing, that's a bigger job than this range covers — which is exactly why circuit testing comes before parts.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0628 for my exact vehicle →
Frequently asked
Can I drive with P0628?
With caution and low expectations. The pump's control circuit is reading wrong, and the failure mode is stalling or not starting. Short necessary trips only until it's diagnosed.
Does 'circuit low' mean my fuel pump is dead?
No — it means the control voltage is lower than expected, which is usually a relay, wiring short, or driver module issue. The pump itself is one possibility, but the cheaper electrical causes are checked first.
What is a fuel pump driver module?
On many vehicles it's a small electronic module that controls pump speed instead of running the pump at full power constantly. When it fails or its connections corrode, control-circuit codes like P0628 appear, often with stalling.
Why does the car cut out at speed with this code?
If the control signal drops out, the pump slows or stops and the engine starves for fuel exactly when demand is highest. Intermittent shorts often behave this way — worse under load, vibration, or heat.
Seeing P0628 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0628 for my vehicleRelated trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0628 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.