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, and the fuel pump itself. A low voltage reading suggests a short to ground, open circuit, or a failing component, which can lead to insufficient fuel pressure and engine performance issues.
1. Most Common Causes
- Faulty fuel pump relay
- Open or shorted wiring in the fuel pump control circuit
- Failed fuel pump
- Blown fuse or fusible link
- Corroded or loose electrical connectors
2. Symptoms You Will Notice
- Engine cranks but does not start
- Engine stalls or hesitates during acceleration
- Check Engine Light illuminated
- Reduced fuel economy
- Fuel pump fuse blows repeatedly
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0628 is present. Check for other related codes.
Step 2: Inspect the fuel pump fuse and relay. Test relay operation with a multimeter.
Step 3: Check voltage at the fuel pump connector. Should be near battery voltage with key on.
Step 4: Inspect wiring and connectors for damage, corrosion, or shorts to ground.
Step 5: If wiring and relay are good, test fuel pump resistance and replace if out of spec.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may stall or fail to start, potentially causing a dangerous situation. Have it diagnosed and repaired immediately.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts like a relay or fuse, but can be higher if the fuel pump needs replacement ($200-$500).
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.