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P0323 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.


P0323 is a Diagnostic Trouble Code (DTC) that is part of the On-Board Diagnostics II (OBD-II) system used in modern vehicles. The Knock Sensor Circuit High Input Problem is a specific issue addressed in this code.


The knock sensor’s abnormally high voltage signal was recognized by the engine control module (ECM), according to the P0323 error code. Engine banging or pinging, which may signify aberrant combustion, is picked up by the knock sensor. A knock situation that may not genuinely exist is detected by the ECM when it gets a high voltage signal from the knock sensor, which might affect the engine’s performance.


The P0323 error code may appear for several reasons, including:

  • Faulty Knock Sensor: The ECM may receive inaccurate voltage signals from a knock sensor that is broken or not working properly.
  • Wiring Issues: Damaged or corroded wiring in the knock sensor circuit can lead to high voltage readings.
  • Engine Mechanical Problems: Problems with engine components, 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 P0323 codes.


The symptoms associated with a P0323 code may include:

  • Reduced engine performance and power.
  • Illumination of the Check Engine Light (CEL) on the dashboard.
  • Potential engine knocking or pinging noises.
  • Decreased fuel efficiency.


To diagnose and confirm a P0323 code, a mechanic or technician will typically perform the following steps:

  • Use an OBD-II scanner to retrieve the trouble codes and freeze frame data.
  • Inspect the knock sensor and its wiring for physical damage or corrosion.
  • Check for loose or disconnected electrical connectors in the knock sensor circuit.
  • Test the knock sensor’s resistance and voltage output.
  • Inspect the engine for mechanical issues that could cause false knock sensor readings.
  • If necessary, test the ECM for faults using specialized diagnostic equipment.

Common mistakes

Common mistakes when dealing with a P0323 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?

Although a P0323 code is not capable of immediately causing engine damage, it should not be ignored. If there is a knock or pinging, failure to adhere to the code could result in reduced engine performance, reduced fuel efficiency, and possibly prolonged engine damage. The situation should be resolved as soon as possible.

What repairs can fix the codeS?

repair manuals

Repairs to address a P0323 code may include:

  • Replacement of the Knock Sensor: If the Knock Sensor is determined to be defective, a new one should be installed.
  • Wiring Repair or Replacement: If corroded or broken wiring is found, it should be fixed or replaced.
  • Fixing Mechanical Engine Issues: If mechanical engine issues are resulting in misleading knock sensor readings, these need to be fixed.
  • Testing and Potential ECM Replacement: If all other options have been exhausted, it may be necessary to test and maybe replace the engine control module.

Related codes

Codes related to P0323 may include:

  • P0324: Knock Control System Error (Circuit Range/Performance)
  • P0325: Knock Sensor Circuit Malfunction


A Knock Sensor Circuit High Input problem is addressed in the P0323 DTC code. It indicates that the engine control module is exposed to an excessive voltage input signal from the Knock sensor, and this may result in a problem with engine performance.

To prevent further damage and restore the vehicle’s performance, prompt diagnosis and repair are required. Failure to do so could have an impact on fuel efficiency and the possibility of engine damage, so it is recommended that this code be addressed as soon as possible.

P0323 Code – What Does It Mean & How To Fix It