P2343 code meaning
Cylinder 8 Above Knock/Combustion Vibration Sensor Threshold
Powertrain system Generic code P23xx codes Check engine light
What P2343 means
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).
P2343 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 8 hours
- Clears after repairAfter a drive cycle
Symptoms of P2343
- Check engine light on
- Pinging or knocking, mostly under load
- Reduced power, possibly less boost on turbo engines
Common causes of P2343
- PossibleCarbon build-up in cylinder 8
- PossibleFuel grade below the requirement
- Less likelyWrong plug type or gap in cylinder 8
- Less likelyCylinder 8 running lean from low injector delivery
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Knock sensorCylinder 8
What each part of P2343 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 43 | The exact fault in that area. |
What to do next
- Note P2343 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2343
What does P2343 mean?
P2343 means "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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2343?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2343 fail an emissions test?
Yes, it can. P2343 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2343 to fix?
Difficulty: medium. A typical repair takes 0.5 to 8 hours of work. This is a job for a workshop.
Will P2343 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.