Powertrain, generic (extended)

P2347 Cylinder 12 Above Knock/Combustion Vibration Sensor Threshold

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2347 ends the per-cylinder knock series that starts with P2336 for cylinder 1; it is the code for cylinder 12 and thus appears only on V12 engines such as those from BMW, Mercedes-Benz, Ferrari or Lamborghini. The engine module has found that the vibration in cylinder 12's combustion window exceeds the threshold and is holding back that cylinder's spark. The J2012 title speaks of a knock or combustion vibration sensor, so the series is not tied to a particular sensor type. No manufacturer was found that documents P2347 publicly; the only bulletin seen for the series, from Stellantis, covers cylinders 1 to 4 of a four-cylinder engine, and GM and Saab use P0324. Work through fuel, deposits, plug and injector of cylinder 12 and check for mechanical noise.

Likely causes

Carbon deposits in cylinder 12
Low-octane or contaminated fuel
Cylinder 12 running lean (restricted injector)
Mechanical noise near the sensor of that bank

Symptoms

  • Check engine light on
  • Reduced power
  • Possibly knocking under load

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–4,000
Time0.5–8 h

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

Parts involved

knock sensorknock sensor wiringcylinder 12 combustion

Related codes

P2346P2345P2336P0324P0330P0312

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