P2338
Cylinder 3 Above Knock Threshold
The knock sensor channel for cylinder 3 has registered combustion noise above the calibrated knock threshold beyond what the spark retard map can correct. Often associated with low-octane fuel, EGR malfunction or carbon-induced hot spots.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Low octane fuel usedCommon
- Carbon deposits causing pre-ignitionPossible
Parts involved
- Knock Sensor
- Spark Plug
P2338 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.