Powertrain, generic (extended)

P2338 Cylinder 3 Above Knock/Combustion Vibration Sensor Threshold

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2338 sets when the knock signal assigned to cylinder 3 rises above its threshold. Because one or two knock sensors serve several cylinders, the module relies on the crank-angle window to tell which cylinder knocked; a code for just one cylinder therefore suggests something local: carbon build-up, a hot spot, a lean-running injector, a wrong spark plug, or mechanical noise that happens to fall into that window. Low-octane fuel tends to raise knock on every cylinder. Stellantis names P2338 with P2336, P2337 and P2339 in bulletin 09-009-26, which covers the 2.0L PHEV engine in Wrangler 4xe and Grand Cherokee 4xe models from Jeep, where foundry sand and machining chips are the cause and the engine is exchanged. Persistent knock can hole or melt pistons, so it should not be ignored.

Likely causes

Carbon build-up or a hot spot in cylinder 3
Injector of cylinder 3 delivering too little (lean, hot combustion)
Engine damage from casting sand or chips (Stellantis 2.0L PHEV)
Knock sensor loose or wrongly torqued, picking up noise

Symptoms

  • Check engine light on
  • Pinging under acceleration
  • Noticeably less 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

Related codes

P2336P2337P2339P0324P0327P0303

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