P0628 code: Fuel Pump A Control Circuit Low
P0628 means fuel Pump A Control Circuit Low. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0628 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.
P0628 symptoms
- 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 P0628
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 →
How to fix P0628
Moderate — doable at home with common tools and patience
- Note exactly how the pump is behaving
Check whether the pump primes at key-on, never runs, or runs nonstop with the key on. Depending on whether the computer switches the ground side or the power side of the relay coil, a control wire shorted to ground can either lock the pump on or keep it off, so the symptom tells you which half of the circuit to suspect.
- Compare the relay against a known-good one
Pull the fuel pump relay and fit an identical spare. A relay with a shorted coil draws more current than the computer's driver expects and can make the control circuit read low; if the code stays away with the new relay, the old one was the cause. Look for heat discoloration on the socket while it's out.
- Hunt for the short to ground
Disconnect the battery, unplug the relay or driver module and the computer connector, and measure from the control wire to a clean chassis ground. It should read open; a low reading means the wire touches metal somewhere, so walk the harness along the frame rail, over the tank straps, and through body seams for rubbed-through insulation.
- Measure the pump's current draw
A worn pump with dragging bearings or a shorted armature pulls more current than a healthy one and can drag down a circuit the module monitors. Clamp a low-amp meter around the pump feed with the engine running and compare against the spec for your vehicle; high or erratic draw makes the pump the root cause.
- Test or replace the driver module
If wiring and pump check out, inspect the pump driver module where fitted for a corroded connector or mounting, a weak ground, or an internal fault. Replace it and clear the code; if it returns with a new module and clean wiring, the engine computer's own driver needs professional diagnosis.
DIY or shop? Relay swaps and watching how the pump behaves need no special skill, and a careful DIYer with a multimeter and wiring diagram can find most shorts to ground along the visible harness. A low-amp clamp meter makes the pump current check straightforward. Shop territory starts when the short is inside a body harness or near the tank, when the pump needs replacing (tank drop or access panel, fuel vapour, new sealing ring), or when the engine computer's driver is the remaining suspect.
Tools for the DIY steps: Digital multimeter · Low-amp clamp meter · Spare fuel pump relay · Wiring diagram for the pump circuit · Flashlight
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0628.
Start a case with P0628 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0628?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0628: common questions
Can I drive with P0628?
Not something a code can answer by itself. The pump's control circuit is reading wrong, and the failure mode is stalling or not starting. Get it diagnosed promptly, and stop driving if the car stalls or hesitates.
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.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0628 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0628 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.