Fuel Pump Control Circuit Low Voltage
The P0628 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the fuel pump control circuit. This circuit includes the fuel pump relay, wiring, connectors, and the fuel pump itself. A low voltage reading suggests excessive resistance, a short to ground, or a failing component, which can lead to insufficient fuel pressure and engine performance issues.
01. Most Common Causes
- Faulty fuel pump relay
- Open or shorted wiring in the fuel pump control circuit
- Failed fuel pump
- Corroded or loose connectors
- Blown fuse
02. Symptoms You Will Notice
- Engine cranks but does not start
- Engine stalls or hesitates during acceleration
- Check Engine Light illuminated
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for additional codes.
Step 2: Inspect the fuel pump fuse and relay; replace if blown or faulty.
Step 3: Check voltage at the fuel pump connector with a multimeter; should be near battery voltage with key on.
Step 4: Test the fuel pump relay and control circuit for continuity and shorts to ground.
Step 5: If voltage is present but pump doesn't run, replace the fuel pump.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may stall unexpectedly or fail to start, leading to a potential accident or being stranded.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and minor repairs like a relay or fuse, but can be higher if the fuel pump needs replacement.