Symptoms of P0329
- Rough idle, shaking, or a stumble under acceleration.
- A flashing check-engine light during an active misfire.
- Power loss and higher fuel consumption.
Common causes of P0329
- Worn spark plugs, ignition coils, or plug wires.
- Fuel-delivery problems — injectors, pressure, or a lean/rich mixture.
- Vacuum leaks, low compression, or a mechanical fault in that cylinder.
Useful checks before replacing parts
- Review freeze-frame data, knock retard, engine temperature, vibration history, and whether the fault appears during acceleration, heat soak, or wet conditions.
- Inspect the sensor connector, harness flex points, shielding, mounting torque, ground quality, and contact with exhaust or rotating components.
- Record knock sensor data during a road test to catch brief signal interruptions or spikes that a static test may miss.
Related OBD-II codes
These nearby ignition / misfire entries can help compare wording and pin down the fault area.