P0329Knock/Combustion Vibration Sensor A Circuit Intermittent
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The knock sensor is a piezoelectric structure-borne sound sensor bolted to the engine block; the module evaluates its signal per cylinder and retards ignition when it detects knock. Sensor A is the first sensor (bank 1 or a single sensor). With a fault the module retards ignition across the board as protection – noticeable loss of power and higher consumption. P0329 reports brief dropouts of the sensor signal – loose contacts, a wire breaking with engine movement and heat, or a loose sensor. No manufacturer document with a threshold for this code was found; GM and Ford cover such faults with their circuit codes, so the description follows CARB's input monitoring requirement.
- What you may notice
- Check engine light on
- Loss of power, sluggish response from ignition retard
- Higher fuel consumption
- Likely causes
- LikelyLoose contact, spread pins or corrosion in the connector
- PossibleWire chafing only with engine movement or heat
- PossibleSensor loose or wrongly torqued
- RareSensor or engine module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.