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P0331 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.


The On-Board Diagnostics II (OBD-II) system used in contemporary automobiles has the Diagnostic Trouble Code (DTC) P0331. The Knock Sensor 2 Circuit (Bank 2) issue is explicitly addressed by this code.


A code of P0331 indicates that an issue is detected with the knock detection circuit in Bank 2, generally referred to as the side without cylinder 1, by the engine control module ECM. Knock sensors are used to detect engine knocking and pinging, which can indicate abnormal combustion. When the ECM identifies a circuit issue, it means that the knock sensor is not functioning as expected, potentially leading to engine performance problems.


Several factors can trigger the P0331 code, including:

  • Faulty Knock Sensor: A malfunctioning or damaged knock sensor can lead to incorrect readings, causing the code.
  • Wiring Issues: Damaged or corroded wiring in the knock sensor circuit can result in poor electrical connections.
  • Loose or Corroded Connectors: Loose or corroded electrical connectors in the knock sensor circuit can disrupt the signal.
  • Engine Mechanical Problems: Engine issues, such as excessive carbon buildup or incorrect spark plug gaps, can cause false knock sensor readings.
  • Faulty ECM: In rare cases, a malfunctioning engine control module can produce erroneous P0331 codes.


  • The following symptoms may be present when a P0331 code is present:
  • Decreased engine power and performance.
  • Illumination of the dashboard’s Check Engine Light (CEL).
  • Possible engine pinging or banging sounds.
  • Fuel economy dropped.


An auto mechanic or technician would normally carry out the following actions to identify and validate a P0331 code:

  • To extract the error codes and freeze frame information, use an OBD-II scanner.
  • Check for corrosion or physical damage on the wire and knock sensor.
  • In the knock sensor circuit, look for disconnected or loose electrical contacts.
  • Check the voltage output and resistance of the knock sensor.
  • Check the engine for any mechanical problems that can result in inaccurate knock sensor readings.
  • If required, use specialist diagnostic tools to check the ECM for issues.

Common mistakes

Common mistakes when dealing with a P0331 code include:

  • Replacing the knock sensor without checking for wiring or connector issues
  • Ignoring other potential causes of engine knocking, such as carbon buildup or spark plug problems,
  • Failing to clear the code and retest the vehicle after making repairs.

How serious is this?

Even while a P0331 code might not immediately harm the engine, it shouldn’t be disregarded. Ignoring the code may result in decreased engine performance, poor fuel efficiency, and even long-term engine damage if banging or pinging occurs. It is advised to deal with this problem right away.

What repairs can fix the codeS?

repair manuals

Repairs to address a P0331 code may include:

  • Replacing the Knock Sensor: If the knock sensor is found to be faulty, it should be replaced with a new one.
  • Repairing or Replacing Wiring: If damaged or corroded wiring is identified, it should be repaired or replaced.
  • Addressing Engine Mechanical Issues: If engine mechanical problems are causing false knock sensor readings, they should be resolved.
  • Testing and Potentially Replacing the ECM: If all other possibilities are ruled out, testing and potentially replacing the engine control module may be necessary.

Related codes

Codes related to P0331 may include:

  • P0328: Knock Sensor 1 Circuit High Input (Bank 1)
  • P0330: Knock Sensor 2 Circuit Malfunction (Bank 2)


Having an issue with the Knock Sensor 2 Circuit (Bank 2) is related to the DTC code P0331. It means that the engine control module has identified a knock sensor circuit malfunction, which might result in performance issues. To stop more damage and improve the performance of the vehicle, prompt diagnosis and repair are crucial. It’s best to deal with this code as soon as you can because ignoring it might result in decreased fuel economy and probable engine damage.

P0331 Code – What Does It Mean & How To Fix It