Cylinder 12 Knock Detected
The P2347 code indicates that the knock sensor has detected excessive vibration or knocking in cylinder 12, which is typically caused by abnormal combustion such as detonation or pre-ignition. This can lead to engine damage if not addressed promptly. The knock sensor monitors engine vibrations and sends a signal to the ECM, which then adjusts timing or fuel mixture to prevent damage. When the threshold is exceeded, the code is set.
1. Most Common Causes
- Low-quality or incorrect octane fuel
- Carbon buildup in cylinder 12
- Faulty knock sensor or wiring
- Engine mechanical issues (e.g., worn bearings, piston slap)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine knocking or pinging noise, especially under load
- Reduced engine performance and fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect knock sensor wiring and connector for damage or corrosion.
Step 3: Perform a cylinder contribution test to isolate cylinder 12.
Step 4: Check fuel quality and octane rating; consider using higher octane fuel.
Step 5: Inspect for carbon buildup using a borescope; clean if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as continued knocking can cause severe engine damage. Have the vehicle inspected as soon as possible.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repairs vary: fuel system cleaning $100-$200, knock sensor replacement $200-$400, or engine repairs $500+.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.