P0628: Fuel Pump A Control Circuit Low

What 'fuel pump A control circuit' means differs by maker: at GM petrol engines it is the control line from the engine module to the fuel pump relay (high-side driver), at GM's LML diesel the lift pump, at Ford petrol engines with a pump driver module the secondary circuit from that module to the pump (reported as a duty cycle on a monitor line), and at Ford's 6.7 L diesel (F-650/750) the high or low side of the pump relay. P0628 means a short to ground: GM detects 0.5 Ω or less to ground with the driver on (8 of 10 samples at 250 ms; two trips in 2018, first trip in 2025); the driver then shuts off, the relay does not pull in and the pump stops. Ford's 6.7 L diesel reports a short to ground on the high side of the pump relay within 0.2 s. Ford petrol engines do not use P0628. A blown fuse is a frequent companion.

Symptoms

• No start or stalling
• Pump does not run
• Blown fuse
• Check engine light on

Most likely causes

• Control wire to relay or pump shorted to ground (chafing)
• Relay coil shorted
• Pump or pump module shorted internally (Ford high side)
• Driver in the engine module faulty

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the pump's fuse, relay, and connector
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Replace the filter if it is due for maintenance
4. Compare commanded and actual pressure in live data
5. Measure the pressure with a suitable gauge
6. Check the sensor and regulator before replacing the pump

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P0628 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 6: Control modules and outputs
• 28: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0628?

Avoid long trips and hard acceleration. If you smell fuel or the car stalls, do not continue.

What causes code P0628?

The most common causes are: control wire to relay or pump shorted to ground (chafing); relay coil shorted; pump or pump module shorted internally (Ford high side).

Related codes

• P0627Fuel Pump A Control Circuit/Open
• P0629Fuel Pump A Control Circuit High
• P062AFuel Pump A Control Circuit Range/Performance
• P0231Fuel Pump Secondary Circuit Low
• P025AFuel Pump Module A Control Circuit/Open

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
• gsi.ext.gm.com: 14OBDG10 Engine Diagnostics
• fordservicecontent.com: obd summary diesel 2023

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.