Cylinder 8 Knock Detected Above Threshold
The P2343 code indicates that the knock sensor has detected excessive vibration or knocking in cylinder 8, exceeding the programmed threshold. This is often caused by abnormal combustion, such as detonation or pre-ignition, which can damage the engine if not addressed. The powertrain control module (PCM) sets this code to alert the driver of potential engine damage.
01. Most Common Causes
- Low octane fuel causing detonation
- Faulty knock sensor
- Carbon buildup in cylinder 8
- Engine mechanical issue (e.g., worn piston, rod bearing)
02. Symptoms You Will Notice
- Check Engine Light on
- Audible knocking noise from engine
- Reduced engine performance
- Poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm code and check for other codes.
Step 2: Inspect knock sensor wiring and connector for damage.
Step 3: Perform a cylinder contribution test to isolate cylinder 8.
Step 4: Check fuel quality and octane rating; consider using higher octane fuel.
Step 5: If no other issues found, replace knock sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with this code can cause severe engine damage due to detonation. Have the vehicle inspected immediately.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repair costs vary: knock sensor replacement $150-$400, carbon cleaning $100-$300, or engine repairs $500+.