When your vehicle’s diagnostic system triggers code P0627, it means the engine control module (ECM) or powertrain control module (PCM) has detected a problem with the fuel pump control circuit. This circuit is responsible for delivering electrical power to the fuel pump, which pressurizes gasoline and sends it to the engine’s fuel injectors. An open circuit—a break in the electrical path—prevents the fuel pump from receiving power, which can leave you stranded or cause your engine to stall unexpectedly.
What Does P0627 Mean?
P0627 is a generic OBD-II diagnostic trouble code that translates to “Fuel Pump Control Circuit/Open.” The code is triggered when the PCM sends a command to activate the fuel pump relay, but the electrical circuit is broken or the signal cannot complete. This prevents the fuel pump from operating, which means fuel cannot be pressurized and delivered to the engine.
The fuel pump control circuit typically includes:
- The fuel pump relay (usually located in the fuse/relay box)
- Wiring harnesses connecting the relay to the fuel pump
- The fuel pump motor itself
- Ground connections and connectors
- The PCM’s fuel pump control output
When any of these components fail or become disconnected, the PCM detects the malfunction and sets code P0627.
Common Symptoms
- No-start condition: Engine cranks but won’t start because no fuel is being delivered
- Engine stalling: Vehicle starts but dies immediately or stalls while driving
- Loss of power: Hesitation or lack of acceleration due to insufficient fuel pressure
- Check Engine Light: Illuminated on the dashboard
- Fuel pump not priming: No buzzing sound from the fuel tank when ignition is turned on
- Intermittent starting issues: Vehicle may start sometimes but not others
- Dead battery warning: In some cases, electrical drain from a faulty relay
Possible Causes (Ranked by Frequency)
1. Faulty Fuel Pump Relay
The fuel pump relay is the most common culprit. This electromechanical switch controls power to the fuel pump. When it fails, the relay cannot close the circuit, preventing fuel pump operation. Relays can fail due to age, electrical surges, or internal contact wear.
2. Broken or Corroded Wiring
Wiring harnesses in the fuel pump control circuit can become damaged from heat, moisture, or physical damage. Corrosion at connectors is especially common in older vehicles or those exposed to salt spray. A single broken wire breaks the entire circuit.
3. Loose or Corroded Connectors
Poor electrical connections at the relay, fuel pump, or PCM can create high resistance or open circuits. Corrosion, loose terminals, or water intrusion are typical causes.
4. Fuel Pump Motor Failure
The fuel pump itself can fail electrically (motor windings open) or mechanically. This is less common than relay failure but still possible, especially in high-mileage vehicles.
5. PCM/ECM Malfunction
In rare cases, the PCM’s fuel pump control output circuit can fail, preventing it from commanding the relay. This typically requires PCM reprogramming or replacement.
6. Ground Connection Issues
A poor or missing ground connection in the fuel pump circuit can prevent current flow, even if other components are functional.
7. Blown Fuse
The fuel pump circuit is typically protected by a dedicated fuse. A blown fuse will open the circuit and trigger P0627.
Diagnostic Steps
Step 1: Verify the Code and Symptoms
Use an OBD-II scanner to confirm code P0627 is present. Note whether the check engine light is constant or intermittent. Try starting the vehicle and listen for the fuel pump prime (a brief buzzing sound from the fuel tank when the ignition is turned on).
Step 2: Check the Fuel Pump Relay
Locate the fuel pump relay in the fuse/relay box (typically under the hood or dashboard). Consult your vehicle’s service manual for the exact location. Remove the relay and inspect it for visible damage, corrosion, or burning. Try swapping it with an identical relay of the same amperage to see if the problem resolves. If the vehicle starts with a different relay, the original relay is faulty.
Step 3: Inspect Wiring and Connectors
Visually inspect all wiring in the fuel pump control circuit for cuts, abrasions, or corrosion. Check connectors at the relay, fuel pump, and PCM. Look for green or white corrosion on terminals. Clean corroded connectors with a wire brush and dielectric grease.
Step 4: Test Fuel Pump Voltage
With the ignition on (engine off), use a multimeter to measure voltage at the fuel pump connector. You should see 12 volts (or close to it). If voltage is absent or very low, the problem is in the control circuit before the fuel pump. If voltage is present but the pump doesn’t run, the pump motor may be faulty.
Step 5: Test the Relay with a Multimeter
Remove the fuel pump relay and test it with a multimeter set to resistance mode. A good relay should show continuity (low resistance) between the control pins when powered. Consult your manual for the specific pin configuration.
Step 6: Check Ground Connections
Verify that all ground connections in the fuel pump circuit are clean and tight. Use a multimeter to measure resistance between the fuel pump ground and the vehicle’s main ground. It should be nearly zero ohms.
Step 7: Scan for Additional Codes
Check for other diagnostic codes that might provide additional clues, such as P0628 (Fuel Pump Control Circuit Low) or electrical codes related to the PCM.
Repair Cost Estimates
Fuel Pump Relay Replacement: $50–$200
- Parts: $15–$50
- Labor: $35–$150
Wiring Repair or Replacement: $100–$500
- Parts: $20–$150
- Labor: $80–$350 (depends on extent of damage and accessibility)
Fuel Pump Replacement: $300–$1,200
- Parts: $150–$600
- Labor: $150–$600 (fuel tank may need to be dropped)
PCM Reprogramming or Replacement: $500–$2,000
- Only necessary if the PCM itself is faulty (rare)
Connector or Ground Repair: $50–$300
- Usually the least expensive fix if corrosion or loose connections are the cause
Can I Still Drive?
Severity: High
Code P0627 indicates a serious problem that affects your vehicle’s ability to run. You should not drive the vehicle if the fuel pump is not operating, as:
- The engine may stall without warning, creating a safety hazard
- You may become stranded if the fuel pump fails completely
- Driving with insufficient fuel pressure can damage the engine
- Continued operation may worsen the underlying problem
If you experience a no-start condition, do not attempt to start the engine repeatedly, as this can drain the battery. Have the vehicle towed to a repair facility for diagnosis and repair.
If the code is intermittent and the vehicle still starts and runs, you may be able to drive carefully to a nearby repair shop, but do so at your own risk and avoid highway driving.