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P0327 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.

Definition

P0327 is an OBD-II Code that refers to Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)

Meaning

A P0327 code is a generic diagnostic trouble code which refers to a knock sensor telling the engine computer when one or more of the engine’s cylinders are “knocking”, that is, combustion of the air/fuel mixture in a way that provides less power and can be harmful to the engine if prolonged. If the knock sensor on Bank 1 is producing a low output voltage (around under 0.5V), it will set the P0327 DTC.

Causes

Common causes for this code include:

  • Bad Knock Sensor
  • Knock Sensor circuit faulty electrical connection
  • Faulty Engine Control Module (rare) 
  • Knock Sensor harness is open or shorted

Symptoms

The symptoms of a P0327 code are:

  • Audible knocking coming from the engine compartment
  • Loss of power
  • Fluctuation in the engine RPM

Diagnosis

To diagnose a P0327 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data
  2. Use a DVOM to check the engine wiring harness for any open or shorted wires
  3. If no problems are found with the electrical system, unplug the knock sensor and use an ohmmeter to test it 
  4. If the resistance of the knock sensor is low (under 0.5 Ohms), replace it 
  5. If you have access to an oscilloscope, you can test the engine computer’s input to the knock sensor circuit for any signs of low voltage 
  6. If everything looks fine, then replace the ECM

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P0327 code:

  • Not properly identifying the cause of the problem when using Freeze Frame Data
  • Not checking the engine wiring harness for shorts and open circuits
  • Not properly testing the knock sensor with an ohmmeter or oscilloscope 
  • Badly calibrated tools
  • Remember: Always use a scan tool to check for codes and do not rely on driver inputs alone. Also, always double check your work and do not overlook the basics.

How serious is this?

A P0327 code is considered to be a low priority Fault Code. This means that it is not likely to cause imminent engine damage, but the underlying problem should be resolved as soon as possible to prevent further damage and restore proper functionality.

What repairs can fix the code?

The following are solutions that may fix this problem:

  • Check for frayed or broken wires leading to the sensor
  • Check for corroded or loose connections
  • Verify the resistance of the knock sensor
  • Make sure the wires and connections that connect to/from the knock sensor and PCM/ECM are intact.
  • Make sure the knock sensor is receiving the proper voltage.
  • Replacing the knock sensor
  • Replacement of the PCM/ECM

Related codes

A P0327 is related to and may be accompanied by the following codes:

P0106 – Intake Air Temperature Circuit Malfunction

P0301 – Cylinder 1 Misfire Detected

P0302 – Cylinder 2 Misfire Detected

P0303 – Cylinder 3 Misfire Detected

P0304 – Cylinder 4 Misfire Detected

Conclusion

In conclusion, the P0327 code is a diagnostic trouble code that refers to a knock sensor of cylinder one inside of the engine telling the Engine Control Module (ECM) of an improperly working knock sensor. The ECM is reliant upon this data to make accurate timing and fuel delivery decisions in order to reduce engine knocking within certain parameters. If the knock sensor on Bank 1 is producing a low output voltage, it will set the P0327 DTC. The most common causes for this code are bad knock sensors, faulty electrical connections, faults with the Engine Control Module (rare), and open or shorted circuits within the engine’s wiring harness or knock sensor itself.