P2339 code meaning
Cylinder 4 Above Knock/Combustion Vibration Sensor Threshold
Powertrain system Generic code P23xx codes Check engine light
What P2339 means
P2339 covers cylinder 4. On a four-cylinder engine this is the last cylinder of the series, which is why Stellantis bulletin 09-009-26 lists exactly P2336 to P2339 for the 2.0L turbo PHEV (sales code ECX, Jeep Wrangler 4xe 2024–2025, Grand Cherokee 2023–2025): any of the four codes with the MIL on, often together with a knocking noise, qualifies for an engine replacement under an extended warranty because of machining debris and casting sand. In general the code means the knock control has seen vibration above the limit in the combustion window of cylinder 4 and retards that cylinder's spark. On six- and eight-cylinder engines the series continues with P2340; GM reports such cases as P0324, and Saab uses the sensor codes P0326/P0331 once more than one cylinder knocks.
P2339 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 13 hours
- Clears after repairAfter a drive cycle
Symptoms of P2339
- MIL on
- Knocking noise from the engine compartment
- Reduced power
Common causes of P2339
- PossibleMachining debris or casting sand damaging the engine (Stellantis bulletin 09-009-26)
- PossibleLow-octane fuel or high intake temperature
- PossibleDeposits raising compression in cylinder 4
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Knock sensorSpark plug
What each part of P2339 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 39 | The exact fault in that area. |
What to do next
- Note P2339 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2339
What does P2339 mean?
P2339 means "Cylinder 4 Above Knock/Combustion Vibration Sensor Threshold". P2339 covers cylinder 4. It is a generic code, so it means the same on every make.
Is it safe to drive with P2339?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2339 fail an emissions test?
Yes, it can. P2339 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2339 to fix?
Difficulty: hard. A typical repair takes 0.5 to 13 hours of work. This is a job for a workshop.
Will P2339 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.