P0628 — Fuel Pump “A” Control Circuit Low #

Note: The exact wording of this DTC (Diagnostic Trouble Code) may differ depending on the OEM (Original Equipment Manufacturer). Always check your vehicle service manual for the most accurate terminology.

• P0628: Fuel Pump “A” Control Circuit Low (General/Generic OBD-II)
• P0628: Fuel Pump Relay Control Circuit Low (Ford, GM)
• P0628: Fuel Pump Circuit Low Input (Chrysler, Dodge, Jeep)
• P0628: Fuel Pump Relay Low Voltage (Toyota, Honda)

Summary of Code P0628 #

P0628 is an OBD-II trouble code indicating that the Powertrain Control Module (PCM) has detected a low voltage condition in the Fuel Pump “A” control circuit. This means that the electrical signal controlling the main fuel pump relay or circuit is lower than expected, which can affect fuel delivery and, ultimately, engine operation. The “A” designation typically refers to the primary circuit in systems with multiple fuel pumps or relays. This code may be triggered by electrical issues, component failure, or wiring faults. Prompt diagnosis is recommended as continued driving with this issue can lead to poor performance or a no-start condition.

Frequent Symptoms for DTC P0628 #

When your vehicle sets a P0628 code, you may notice several symptoms. The severity can range from subtle to severe, depending on how the fuel pump circuit is affected. Common symptoms include:

• Engine cranks but will not start
• Engine stalling or hesitation under load
• Reduced engine performance or power loss
• Illuminated Check Engine Light
• Longer than usual engine cranking times
• Poor fuel economy
• Intermittent starting issues

Most Likely Causes for DTC P0628 #

P0628 can be triggered by several issues, most of which are electrical in nature. The following are the most common causes, listed in order of likelihood:

1. Faulty fuel pump relay (sticking or burned contacts)
2. Open or shorted wiring in the fuel pump “A” control circuit
3. Defective fuel pump (internal short or high resistance)
4. Corroded or loose electrical connectors at the relay, pump, or PCM
5. Failed PCM (rare)—internal driver circuit malfunction
6. Blown fuse or poor ground connection in the fuel pump circuit

Step-by-Step Diagnostic for P0628 #

Diagnosing P0628 requires following a logical path, starting with the simplest checks and moving toward more involved testing. Here’s a recommended approach:

• 1. Scan for additional codes and record freeze frame data. Other codes may offer clues.
• 2. Visually inspect all wiring and connectors related to the fuel pump circuit for damage, corrosion, or loose connections.
• 3. Check the fuel pump relay: Swap with a known good relay if possible or bench-test the relay for proper operation.
• 4. Test voltage and ground at the fuel pump connector while attempting to start the engine. Use a digital multimeter.
• 5. Check fuse(s) associated with the fuel pump circuit. Replace any blown fuse and investigate the cause.
• 6. Perform continuity and resistance checks on the control circuit wiring from the PCM to the relay and from the relay to the fuel pump.
• 7. If all wiring and relays test OK, test the fuel pump for internal resistance and operation.
• 8. As a last resort, check for PCM control circuit output and, if faulty, consider PCM replacement or repair.

Possible Repairs for P0628 #

Once you’ve identified the root cause, repairs for P0628 are typically straightforward and directly related to the faulty component or wiring. Common repairs include:

• Replacing a faulty fuel pump relay
• Repairing or replacing damaged wiring or connectors in the control circuit
• Replacing a defective fuel pump assembly
• Cleaning or tightening corroded electrical connections
• Replacing a blown fuse and addressing the underlying cause
• Rarely, repairing or replacing the PCM (after confirming all other components are good)

Is It Safe to Drive with Code P0628? #

Generally, it is NOT recommended to drive with a P0628 code. This code directly affects the fuel delivery system, and your vehicle may stall, fail to start, or experience sudden power loss—posing a safety risk, especially at higher speeds or in traffic. In some cases, the vehicle may run intermittently or not at all. It’s best to address this code promptly before further damage or a no-start situation occurs.

Vehicles Most Commonly Affected by P0628 #

While P0628 is a generic OBD-II code and can theoretically appear on any vehicle with electronic fuel injection, it is most frequently reported on:

• Ford (Focus, Fusion, F-Series)
• Chevrolet/GMC (Silverado, Malibu, Trailblazer)
• Chrysler, Dodge, Jeep (Ram, Charger, Grand Cherokee)
• Toyota (Camry, Corolla, Tacoma)
• Honda (Accord, Civic)
• Volkswagen (Jetta, Passat)

Keep in mind that fuel pump circuit designs and diagnostic strategies vary between brands, so always consult OEM-specific resources for accurate troubleshooting.

Common Mistakes & Best Practices for P0628 #

Technicians and DIYers sometimes make critical mistakes when diagnosing and repairing P0628. Avoid the following errors:

• Replacing the fuel pump without first confirming voltage supply and ground integrity
• Overlooking relays or fuses as the root cause
• Ignoring corroded or loose connectors, especially in older vehicles
• Failing to check for related codes that may point to broader electrical issues
• Not using a wiring diagram to trace the circuit

Best practices: Always begin with a thorough visual and voltage check, use the correct wiring diagrams, and only replace major components after verifying all other circuit parts.

Express FAQ for Code P0628 #

Q: Will a P0628 code always mean I need a new fuel pump?
A: No. While a bad fuel pump is possible, P0628 often points to a relay, wiring, or fuse problem. Always diagnose the circuit fully before replacing the pump.

Q: Can I clear this code and keep driving?
A: Clearing the code without addressing the cause is not recommended. The issue may return immediately, and your car could stall unexpectedly or fail to start when you need it most.