Generic fault code
P2339 — Cylinder 4: knock/combustion vibration above sensor threshold
The control unit stores code P2339 when it detects this fault: “Cylinder 4: knock/combustion vibration above sensor threshold”.
Indicative severity: MediumIgnition and misfire
Reviewed by Daniel Morales, founder of Reprorace SL, on
What does code P2339 mean?
Spark plugs and coils make the spark that burns the mixture in each cylinder. If a cylinder does not fire properly, the engine shakes and loses power, and unburnt fuel can damage the catalytic converter.
- System
- P · Powertrain
- Area
- Ignition and misfire · Car system: Ignition
- Type
- Generic (SAE J2012 / ISO 15031-6): the same meaning on every make
- Indicative severity
- Medium. Diagnose soon: it may raise emissions or consumption, or trigger limp-home mode.
What usually causes code P2339?
- Incorrect fluid level or quality (oil, coolant, fuel, reductant)
- Component stuck or fouled (carbon deposits)
The most likely causes come first. Only a check on the car confirms which one is yours.
What are the symptoms of code P2339?
- Misfires or a rough-running engine
- Harder starting or jerking when accelerating
- Higher fuel use and less power: the engine may retard the ignition to protect itself
These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.
Can I keep driving with code P2339?
With care, and not for long. You can take the car to a workshop, ideally without long trips or heavy loads, and without putting it off: fuel use or emissions may rise and the car may go into limp-home mode (less power). If the light flashes, a red warning light comes on, the temperature rises or you notice a loss of power, noises or smoke, stop as soon as it is safe.
This is guidance only: only someone who checks the car can say whether it is safe to drive.
An indicative description of the code's generic meaning. Each manufacturer may give it a different meaning, conditions or tests: always follow its service information and your workshop's advice.
What you can do yourself
For this kind of fault
With the engine off, check that the coil connectors are pushed fully home. If the code names a knock sensor, use fuel with the octane rating your owner's manual asks for.
Read the code and keep the report: with an ECO-LITE in the OBD socket you see it on your phone or computer, with the data captured when the fault happened.
Look for anything obvious: a loose connector, a disconnected hose, a fuel cap not closed properly or a low fluid level. Do not take apart anything you do not know.
Clear the code only after writing it down or after the repair. Clearing turns the light off, but it also deletes the freeze-frame data and the readiness monitors used at the inspection.
Drive normally for a few days and read the codes again. If the code comes back, the fault is still there: book the workshop and bring the report.
Read your car's fault codes on your phone
With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.
Related codes
- P2303Ignition coil B, primary control circuit: signal low
- P2304Ignition coil B, primary control circuit: signal high
- P2305Ignition coil B, secondary circuit: malfunction
- P2336Cylinder 1: knock/combustion vibration above sensor threshold
- P2337Cylinder 2: knock/combustion vibration above sensor threshold
- P2338Cylinder 3: knock/combustion vibration above sensor threshold
P23xx codes: ignition coils and knock
In the glossary
Read more: Remote OBD diagnostics: what it is, how it works and what it can't do