Powertrain, generic (extended)

P2339 Cylinder 4 Above Knock/Combustion Vibration Sensor Threshold

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

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.

Likely causes

Machining debris or casting sand damaging the engine (Stellantis bulletin 09-009-26)

Low-octane fuel or high intake temperature

Deposits raising compression in cylinder 4

Symptoms

MIL on
Knocking noise from the engine compartment
Reduced power

Repair estimate

DifficultyHardWorkshop job

Parts and labour€0–8,000

Time0–13 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

knock sensorspark plug

References: static.nhtsa.gov, saabwisonline.com, en.wikipedia.org, law.cornell.edu.