P2343 Cylinder 8 Above Knock/Combustion Vibration Sensor Threshold

P2343 belongs to cylinder 8, the last cylinder of a V8, and is stored when the knock intensity measured in that cylinder's crank-angle window stays above the calibrated limit. The knock control first answers with spark retard for cylinder 8 alone, and on turbocharged engines it may also lower boost; the code marks that this cylinder keeps knocking. Prolonged detonation can melt or hole a piston or crack the head, so the cause matters more than the light. Typical checks are fuel grade, carbon in cylinder 8, plug type and gap, injector delivery and, if the noise is mechanical, the parts near that bank's sensor. No manufacturer publishes P2343 in openly available documents; GM and Saab cover the same case with P0324 (one cylinder knocking for over 8 s).

Likely causes

Symptoms

• Check engine light on
• Pinging or knocking, mostly under load
• Reduced power, possibly less boost on turbo engines

Repair estimate

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

Parts involved

Related codes

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