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P0231 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


Let us define the P0231 DTC code to begin with. The DTC codes are a standard code for communicating specific problems on your vehicle’s onboard computer (ECU). P0231 is the code related to a secondary fuel pump circuit, which means that there’s a low voltage condition in it.


It is essential that we understand the meaning behind the P0231 code in order to diagnose and solve this problem. Basically, P0231 indicates that there has been a greater reduction in voltage than estimated in the fuel pump’s second circuit. This can make it difficult to get the fuel pump working properly, which may affect your vehicle’s performance.


Let’s now examine the P0231 code’s common causes. This problem may be caused by a number of circumstances, including:

  • Faulty Fuel Pump: A faulty fuel pump may not receive enough electricity to perform properly.
  • Inadequate Fuel Pump Relay: The relay for the fuel pump is in charge of turning on the fuel pump. Low voltage in the circuit may result if it is defective.
  • Wiring or Connection Issues: Damaged or corroded wiring, poor connections, or loose terminals in the fuel pump secondary circuit can result in low voltage.


You can find the problem early if you can identify symptoms connected to the P0231 error code. Typical signs include:

  • Decreased Engine Performance: Your car can struggle to accelerate and have limited power output.
  • Stalling or Rough Running: Engine stalling or running roughly can occur due to inadequate fuel delivery.
  • Hard Beginning: Due to inadequate fuel pressure, you can have trouble starting your car.


It is essential that a precise diagnosis be made in order to adequately resolve the P0231 code. The precise problem may be detected by a professional mechanic or diagnostic tool. In order to determine the main cause, it usually performs tests for fuel pumps, relays, and related components.

Common mistakes

In order to prevent unnecessary time and resources, there is a need to avoid all types of mistakes in the diagnostic and repair processes. Misdiagnosis of the problem as a faulty fuel pump when the relay is the actual cause of the problem or neglecting to check for the problem with the wires are some of the common errors.

How serious is this?

It is important to understand the severity of the P0231 code. In spite of the fact that your vehicle can continue to run with this problem, disregarding it may result in additional damage, decreased fuel efficiency, and possibly life-threatening situations such as stalling. It is important to deal with this without delay.

What repairs can fix the codeS?

repair manuals

Depending on the underlying problem, a number of remedies can resolve the P0231 error code after diagnosis. Possible fixes might be:

  • If the fuel pump is determined to be defective, replace it.
  • Changing the relay for the fuel pump.
  • Fixing or repairing the fuel pump secondary circuit’s broken wiring or connections.

Related codes

You don’t usually get a sense of anxiety when the check engine lights come on in your car. P0231 is a code that may be found on the fuel pump’s Secondary Circuit, which means it has an inadequate voltage condition. Nevertheless, it might be helpful to understand the codes of P0231 as they relate to possible issues in the inner workings.

  • P0232 Fuel Pump Secondary Circuit High: This code is the equivalent of P0231. P0232 indicates a high voltage in the fuel pump’s secondary circuit, while P0231 is indicative of low voltage. Either of these conditions may interrupt The fuel pump operation and should be rectified as soon as possible.

  • P0233 fuel pump secondary circuit intermittent: As opposed to P0231 and P0232, P0233 indicates that there is an intermittent problem with a fuel pump secondary circuit. This suggests that the low or high voltage condition is not constant, but it does occur periodically. Diagnosing this intermittent issue may be more complicated, but it is also essential to resolve it.


In conclusion, the P0231 DTC code indicates a low voltage condition within the fuel pump’s secondary circuit. Failure to comply with this code can lead to poor vehicle performance and, in some cases, dangerous situations. 

In order to effectively address this problem and ensure that your vehicle operates properly again, you need to understand what it means, the nature of its problems, how they are related, and any necessary repairs. If you encounter the P0231 code, seek medical advice immediately for diagnosis and repair of the problem.

P0231 Code – What Does It Mean & How To Fix It