P0628 Fuel pump: signal or voltage too low ("A")

By: Diagno editorial team · Updated: 2026-10-15

P0628 means: Fuel pump: signal or voltage too low ("A"). The fuel pump delivers fuel from the tank to the engine. Don't drive until the car has been checked. The engine could be damaged. The repair usually costs about €40–300 in Estonia. The most common cause: connector loose, damp or corroded.

What it means

The fuel pump delivers fuel from the tank to the engine. The computer found a fault in the pump supply or control. The signal voltage is too low. Usually a wire is broken, a connector is loose or a wire is shorted to ground.

What you may notice

• No start or hard starting
• The engine cuts out while driving
• Less power

What could be wrong

1. 1Connector loose, damp or corroded
2. 2Wire broken or shorted to ground
3. 3Faulty fuel pump
4. 4Engine computer fault (rare)

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Switch the ignition on and listen for the pump humming from the tank for a couple of seconds. Check the fuse. Best left to a workshop. It needs a diagnostic tool and experience.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the fuel pump

Standard SAE description: Fuel Pump "A" Control Circuit Low