Symptoms of P0343
- 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 P0343
- 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
- Check for short-to-voltage, open ground, poor connector contact, and harness damage near the cam sensor.
- Compare cam and crank synchronization data while watching for dropouts, stuck values, or implausible cam movement.
- Inspect recent timing, valve-cover, or sensor service that may have disturbed wiring or sensor mounting.
Related OBD-II codes
These nearby ignition / misfire entries can help compare wording and pin down the fault area.