P0328

What it means

P0328 means the engine control unit has seen a signal voltage from knock sensor A (usually bank 1) that is higher than expected for longer than allowed. The knock sensor normally produces a small, varying signal as it detects engine vibration. A signal stuck high suggests a short to voltage, a wiring fault or a faulty sensor, so the unit cannot rely on it to detect detonation.

Symptoms

• Check engine light on
• Reduced power or sluggish acceleration as the ECU retards ignition timing
• Poorer fuel economy
• Pinking or rattling under load if detonation is not being controlled
• Rough running or hesitation in some cases

Possible causes

• Faulty knock sensor producing a high or stuck signallikely
• Damaged, chafed or corroded wiring to the knock sensor, including a short to voltagelikely
• Poor connection or corroded terminals at the sensor or ECU connectorlikely
• Incorrect sensor tightening torque or poor mounting contact giving false signalspossible
• Electrical interference from nearby faulty components or poor earthspossible
• Fault inside the engine control unitrare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data such as engine load, temperature and rpm
2. Check for other related codes, such as other knock sensor or reference voltage faults, which can point to a shared wiring problem
3. Inspect the knock sensor harness and connector for chafing, heat damage, oil contamination, water ingress and corrosion
4. Check the sensor is fitted correctly and tightened to the manufacturer's specified torque, with nothing between it and the block
5. Back-probe or test the circuit with a multimeter for a short to voltage, open circuit and resistance, following the wiring diagram for that model
6. Check the sensor signal on a scope or live data while the engine runs, comparing it with the manufacturer's specification, as sensor type and location vary by engine
7. Check the ECU supply, reference and earth circuits before suspecting the control unit
8. Clear the code and road test to see if it returns

How to fix

• Replace the knock sensor if it fails electrical or signal tests, fitting it to the correct torque
• Repair or replace damaged wiring or the connector, ensuring correct routing and securing
• Clean and refit corroded connections, replacing terminals where needed
• Repair faulty earths or supply circuits found during testing
• Repair or replace the engine control unit only after all wiring and sensor faults are ruled out, as a last resort

Can I keep driving?

Nearby codes

• P0327GenericKnock/Combustion Vibration Sensor A Circuit Low
• P0329GenericKnock/Combustion Vibration Sensor A Circuit Intermittent