OBD-II code · Powertrain (generic, extended)
P2339 Cylinder 4 Above Knock Threshold
The knock sensor channel for cylinder 4 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.
Is it safe to drive with P2339?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyLow octane fuel used
- PossibleCarbon deposits causing pre-ignition
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Knock Sensor, Spark Plug
Related codes
- P2336Cylinder 1 Above Knock Threshold
- P2337Cylinder 2 Above Knock Threshold
- P2338Cylinder 3 Above Knock Threshold
- P2340Cylinder 5 Above Knock Threshold
- P2341Cylinder 6 Above Knock Threshold
- P2342Cylinder 7 Above Knock Threshold
- P2343Cylinder 8 Above Knock Threshold
- P233AFuel Pressure Regulator C Control Circuit Open
- P233BFuel Pressure Regulator C Control Circuit Low
- P233CFuel Pressure Regulator C Control Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.