Ignition

P0325 — Knock Sensor 1 Circuit Malfunction (Bank 1)

Severity: medium Drive with care, to a shop

What P0325 means

The knock sensor is a piezoelectric sensor mounted on the engine block that listens for vibrations and sends a signal to the engine control unit. The ECU uses it to detect knock (pinging) and adjust ignition timing. P0325 is set when the signal from sensor 1 is missing or out of range, or the circuit is open or shorted.

Symptoms

  • Check Engine Light on
  • Reduced power and sluggish acceleration
  • Worse fuel economy
  • Pinging or knocking noise under load
  • Rough running under heavy throttle

Possible causes

  1. Failed knock sensor
  2. Damaged wiring or corroded connector in the sensor circuit
  3. Open circuit or short to ground or power in the harness
  4. Loose sensor or incorrect mounting torque
  5. ECU fault or software issue (rare)

How to diagnose

  1. Read the codes and freeze-frame data, clear the code and see if it returns
  2. Inspect the sensor harness and connector for chafing, oil contamination, corrosion and poor contact
  3. Confirm the sensor is mounted tightly, torqued to spec, and seated on a clean surface
  4. Measure the sensor resistance and circuit voltage per the manufacturer's specifications
  5. Test the wiring between the sensor and ECU for opens and shorts to ground
  6. Use a scope to check for a signal when tapping the engine near the sensor
  7. If the sensor and wiring are good, check ECU power, grounds and the ECU itself

Common fixes

  • Replace the knock sensor
  • Repair damaged wiring and clean or replace the connector
  • Reinstall the sensor with the correct torque on a clean mounting surface
  • Reflash or replace the ECU only if it is proven faulty

P0325 on different brands

Ford · manuals
Ford uses the extended code P0325:01 in its 2024-2025 gasoline-engine monitoring strategy to flag the knock sensor 1 circuit; it identifies the condition the monitor detected, not necessarily a failed sensor.

Questions and answers

Can I drive with a P0325 code?

Briefly and gently, yes, but expect lower power and worse fuel economy. Get it diagnosed soon to avoid risking the engine.

What most often causes P0325?

A bad knock sensor or damaged wiring and a corroded connector are the most common causes. Start by inspecting the harness and checking the sensor's torque.

Should I replace the sensor right away?

No, check the wiring, connector and mounting first. Replace the sensor only if the circuit is good and the sensor's readings or signal are out of spec.

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.