P2344
Cylinder 9 Above Knock/Combustion Vibration Sensor Threshold
The knock or combustion-vibration sensor monitors the structure-borne noise of each cylinder. The signal level for cylinder 9 has stayed above the diagnostic threshold for an extended period, indicating either persistent knock or an electrical fault that biases the channel high.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Persistent knocking on cylinder 9 (low-octane fuel, carbon deposits, hot spot)Common
- Sensor or wiring biased high by short or moisturePossible
- Mechanical knock from bearings, piston pin or wrong torqueLess likely
Parts involved
- Knock Sensor
- Knock Sensor Wiring
- Fuel Octane Quality
- Cylinder 9 Combustion
P2344 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.