Engine

P0328 — Knock Sensor 1 Circuit High Input (Bank 1)

Severity: medium Drive with care, to a shop

What P0328 means

A knock sensor is a piezo element bolted to the engine block that listens for vibrations and sends a voltage signal to the engine computer, which uses it to detect detonation. P0328 sets when the circuit voltage for bank 1 stays higher than expected. The cause can be the sensor, the wiring, or genuine engine knock.

Symptoms

  • Check Engine light on
  • Rough or uneven idle
  • Loss of power or hesitation
  • Pinging or knocking under load
  • RPM fluctuating at steady speed
  • Reduced fuel economy

Possible causes

  1. Failed knock sensor
  2. Damaged wiring or corroded connector
  3. Signal wire shorted to voltage
  4. Open circuit in the sensor wiring
  5. Sensor over- or under-tightened
  6. Fault in the engine computer input circuit
  7. Real detonation from poor fuel, overheating or wrong timing

How to diagnose

  1. Scan for codes and freeze frame data, and note any ignition or fuel codes
  2. Inspect the sensor connector and harness for chafing, corrosion and moisture
  3. Check the sensor's mounting torque and that it sits flat on the block
  4. Measure sensor resistance and voltage against the factory spec
  5. Test the signal wire for a short to power or an open, and check shield and ground
  6. Listen for actual engine knock and check fuel quality and spark plugs
  7. Watch timing and knock retard data on a scan tool
  8. If the sensor and wiring are good, check the computer's input circuit

Common fixes

  • Replace the knock sensor and torque it to spec
  • Repair the harness and clean or replace the connector
  • Fix the cause of real knock: fuel, plugs, overheating, carbon buildup
  • Replace or reprogram the engine computer (rare, last resort)

Questions and answers

What does P0328 mean?

The engine computer is getting an abnormally high signal from knock sensor 1 on bank 1. The usual causes are a bad sensor, a wiring short to voltage or a poor connection.

Can I drive with P0328?

For a short time, yes, but avoid heavy loads. Knock protection may not work and power may be reduced.

How do I test a knock sensor?

Inspect the connector and wires, check the torque, then measure resistance and voltage per your vehicle's spec. A scan tool can also show whether the signal reacts when you tap near the sensor.

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.