P0628 — Fuel pump control circuit voltage is too low
The engine's computer detects a low voltage or poor signal in the fuel pump control circuit. This usually means the fuel pump isn't getting enough power or the wiring is faulty, causing the pump to underperform or stop working. It triggers this code to protect the engine from running lean or stalling due to insufficient fuel delivery.
Common causes
The cause is almost always one of a few things. Here they are — P0628 rarely comes from anything outside this list:
- Faulty fuel pump relay or fuse
- Damaged or corroded wiring/connectors to fuel pump
- Failing fuel pump motor
- Defective fuel pump control module
- Poor ground connection for fuel pump circuit
Where to start
In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:
- Check and replace blown fuses or faulty relays
- Inspect and repair wiring and connectors
- Test fuel pump voltage and replace pump if needed
- Check fuel pump control module operation
- Verify and clean ground connections
That is what holds for P0628 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.
Why TorqFix for your car?
Above is what the code means and why it appears. TorqFix goes further — it gives you specific procedures, torque values, wiring diagrams and pinouts for your exact engine, not generic steps for every car. Real workshop data (127,000+ diagrams, 10,000+ procedures), interpreted by AI in your language.
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Code breakdown
🔧 Related repair procedures
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- VW: Installing and removing unit injector
- AUDI: Testing injectors
- VW: Checking injectors
- AUDI: Intake manifold (bottom section), fuel rail, injector - exploded view
- VW: Checking return flow rate of injectors with engine running
- VW: Removing and installing injectors, direct injection
- AUDI: Removing and installing injectors - magnesium intake manifold
- AUDI: Renewing seals on injectors
Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
The same code can mean different things on different makes. Match the meaning to your make before acting on it.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
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