Engine

P0327 — Knock Sensor 1 Circuit Low Input

Severity: medium Drive with care, to a shop

What P0327 means

The engine control module monitors the knock sensor, which listens to vibrations in the engine block to detect abnormal combustion (knock or pinging). P0327 sets when the signal voltage in the knock sensor 1 circuit falls below the expected range. Without a reliable signal, the module cannot detect knock accurately and typically retards ignition timing to protect the engine.

Symptoms

  • Check Engine light on
  • Sluggish acceleration and reduced power
  • Pinging or knocking under load
  • Rough idle or hesitation
  • Worse fuel economy
  • Retarded ignition timing

Possible causes

  1. Failed knock sensor
  2. Open circuit or short to ground in the sensor wiring
  3. Corroded or loose connector
  4. Sensor loose or tightened to the wrong torque
  5. Damaged wire shielding or water in the connector
  6. Rarely, a fault in the module's input circuit

How to diagnose

  1. Scan for codes and freeze frame data, clear the code, and see if it returns
  2. Inspect the sensor, connector, and harness for cracks, chafing, oil, and corrosion
  3. Confirm the sensor sits flat against the block and is tightened to spec
  4. Test the signal wire and shield for opens and shorts to ground
  5. Check sensor resistance and output against factory specs (a light tap near the sensor should change the signal)
  6. Check reference voltage and ground at the connector on the module side
  7. If the wiring is good, replace the sensor and retest
  8. Suspect the control module only as a last resort

Common fixes

  • Replace the knock sensor and torque it to spec
  • Repair or replace damaged wiring and connectors
  • Clean the mounting surface and contacts and secure the sensor
  • Repair or reflash the control module if confirmed faulty

Questions and answers

What does P0327 mean?

It means the knock sensor 1 circuit is sending a signal that is too low. The sensor itself or its wiring is the most common culprit.

Can I drive with P0327?

Briefly and gently, yes, but the engine's protection against knock is reduced. Fix it soon and use good-quality fuel in the meantime.

Can I just clear the P0327 code?

Clearing it will turn off the light for a while, but the code will return if the cause remains. Check the sensor, connector, and wiring first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.