P0628 Fuel Pump A Control Circuit Low
OBD2 Error Codes

P0628 Fuel Pump A Control Circuit Low

05.10.2023 /

P0628 – OBD-II Trouble Code Technical Description

Fuel Pump A Control Circuit Low

What does the fault code mean P0628?

Diagnostic code P0628 applies to a variety of OBD-II vehicles, including Ford, Dodge, Toyota, Chrysler, Jeep, Ram, Chevrolet, Nissan, Mitsubishi, Mercedes and others. This code indicates a problem in the fuel pump “A” control circuit due to low voltage. This may be caused by damaged wires, connectors, or Controller Area Network (CAN). The powertrain control module (PCM) or engine control module (ECM) often sets this code, but other modules such as the fuel control module or fuel injection control module can also cause it.

The fuel pump is critical to delivering fuel to the engine. An open in the control circuit can also cause code P0628. It is recommended that you do not continue driving with this code, but rather take it to a repair shop to diagnose and repair the problem. This code indicates a violation of the voltage parameters in the fuel pump control circuit set by the manufacturer.

Typical fuel pump:

Associated fuel pump A control circuit codes include: P0627 Fuel pump A control circuit/open P0628 Fuel pump A control circuit low P0629 Fuel pump A control circuit high P062A Fuel control circuit range/performance pump "A"

Possible reasons

Code P0628 usually occurs for the following reasons:

  1. Faulty fuel pump.
  2. Open or shorted wires associated with the fuel pump.
  3. Poor electrical connection between the system and the fuel pump.
  4. Failure of the fuel pump relay.
  5. Malfunction of the fuel pump control module (if installed).

The P0628 code may be caused by the following:

  1. Problems with the fuel pump itself.
  2. Damaged or broken ground wire in the device control module.
  3. Loose ground wire in control module.
  4. Broken, shorted or corroded wires in the CAN bus (Controller Area Network).
  5. CAN bus fault.
  6. Connectors and wires that are not secured properly can cause them to wear out or break the circuit.
  7. High resistance in a circuit, such as caused by melted or corroded connectors or internal wire corrosion.

These reasons can lead to a P0628 code, indicating a voltage violation in the fuel pump control circuit set by the manufacturer.

What are the symptoms of a fault code? P0628?

Symptoms of a P0628 trouble code may include:

  1. Check Engine light is on.
  2. Problems with starting the engine.
  3. Misfire or engine stalling.
  4. The engine stalls after starting.
  5. Reduced fuel economy.
  6. The engine rotates normally, but cannot be started.
  7. The engine stalls when it reaches operating temperature.

Note: The check engine light may not come on immediately, and the problem may not be resolved until the vehicle has been driven several times. That is, if the CEL (check engine) light does not come on after using the car for a week, the problem has probably been fixed.

Additionally, when the P0628 code is stored, the fuel cap warning light may also illuminate. These symptoms are usually associated with this code.

How to diagnose a fault code P0628?

Diagnosing the P0628 code involves the following steps:

  1. Use an OBD-II scanner to check the codes in the PCM.
  2. Perform a visual inspection of the wiring and connectors to rule out problems in the fuel pump control circuit.
  3. Clean up the code and retest the system to make sure the problem is resolved.
  4. If necessary, repeat the diagnostics at each stage and erase the codes again.
  5. Check the Technical Service Bulletins (TSB) for your specific vehicle.
  6. Scan and test each module using an OBD-II scanner.
  7. Check the condition of the connectors and wiring for damage.
  8. Check ground connections and repair any corrosion or damage.
  9. Use the wiring diagram to determine the location of the open circuit if this is the cause of the P0628 code.
  10. Repair or replace damaged wires.
  11. Use a multimeter to measure the resistance in the circuit and determine the location of the short or open.
  12. Use a power probe if the fault in the circuit cannot be found.

Please note that specific technical data and service bulletins for your vehicle should always take precedence.

Diagnostic errors

When a communication code such as P0628 is stored, other trouble codes can often be stored along with it. In such cases, often the first step is to look for additional codes and symptoms. It is important to note that these additional codes will usually resolve when the underlying fault associated with the P0628 code is resolved.

How serious is the fault code? P0628?

Code P0628 sometimes does not seem serious as it is usually not accompanied by noticeable symptoms other than the check engine light and fuel cap light coming on. However, it is worth remembering that this code can cause other fault codes to be activated, which in turn can seriously affect the performance of your vehicle. If this code is not resolved, it can cause permanent damage to your vehicle, so it is important to take steps to resolve it as soon as possible.

What repair will help eliminate the code? P0628?

There are several common repairs to resolve the P0628 code:

  1. Repair or replacement of the fuel pump relay: The cause of the P0628 code may be a faulty or damaged fuel pump relay. In this case, a mechanic can repair or replace this relay.
  2. Repair or replacement of wires and connectors: Open or shorted wires and faulty connectors can cause this code. Repairing or replacing damaged wiring elements will solve this problem.
  3. Replacing the fuel pump harness: If the P0628 code is due to a problem in the fuel pump harness, the harness will need to be replaced.
  4. Replacing a faulty fuel pump: If after checking it is discovered that the fuel pump is not functioning properly, it should be replaced with a working one.

Repair work may vary depending on the specific case and vehicle make. It is important to have your vehicle diagnosed and repaired as recommended by a professional mechanic to avoid additional problems and ensure reliable vehicle performance.

What is P0628 Engine Code [Quick Guide]

P0628 – Brand-specific information

The P0628 code can have different interpretations and causes depending on the specific make and model of the vehicle. Here are some of them:

  1. Ford:
  1. Dodge / Chrysler / Jeep:
  1. Toyota:
  1. Chevrolet:
  1. Nissan:
  1. Mitsubishi:
  1. Mercedes-Benz:

It is important to note that the meaning of the codes may vary slightly depending on the specific model and year of the vehicle. When diagnosing and repairing, it is recommended that you refer to the official repair and service manuals for the specific make and model of your vehicle.

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