What Does P0628 Mean?
The PCM has detected a low voltage condition in the fuel pump 'A' control circuit. The control signal to the fuel pump relay or fuel pump driver module is being pulled low when it should not be, indicating a short to ground in the circuit. This can cause the fuel pump to run continuously or prevent proper fuel pressure management.
Safety Warning
A shorted fuel pump circuit can cause the pump to run with key off (fire risk) or prevent proper fuel delivery. Address immediately.
Common Causes
40%
Short to ground in the fuel pump control circuit wiring
25%
Faulty fuel pump relay with internally shorted coil
20%
Failed fuel pump driver module with shorted output
15%
PCM internal driver shorted to ground
Diagnostic Steps
1
Step 1: Remove the fuel pump relay and measure resistance from the PCM control terminal in the relay socket to chassis ground — should be infinite (OL). If low resistance, the wire is shorted to ground.
2
Step 2: Disconnect the PCM connector and recheck the same wire for shorts to ground — if the short disappears, the PCM driver is internally shorted.
3
Step 3: Inspect the fuel pump control wiring for damage, especially where it routes near the exhaust, frame rails, or sharp body edges.
4
Step 4: If a fuel pump driver module is present, disconnect it and check the control wire segment by segment to isolate the short.
5
Step 5: Repair any damaged wiring, replace the relay or FPDM as indicated by testing.
Estimated Repair Cost
$50 - $600
Parts + labor, varies by vehicle and location
The PCM has detected a low voltage condition in the fuel pump 'A' control circuit. The control signal to the fuel pump relay or fuel pump driver module is being pulled low when it should not be, indicating a short to ground in the circuit. This can cause the fuel pump to run continuously or prevent ...
The most common cause of P0628 (Fuel Pump "A" Control Circuit Low) is: Short to ground in the fuel pump control circuit wiring
Typical repair costs for P0628 range from $50 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A shorted fuel pump circuit can cause the pump to run with key off (fire risk) or prevent proper fuel delivery. Address immediately.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0628 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
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