Cylinder 3 Knock Detected
The P2338 code indicates that the engine control module (ECM) has detected knock (detonation) in cylinder 3 that exceeds the normal threshold. This is often caused by improper air-fuel mixture, low-octane fuel, carbon buildup, or mechanical issues like a faulty knock sensor. Continued operation can lead to severe engine damage.
01. Most Common Causes
- Low-octane fuel or poor fuel quality
- Carbon buildup in cylinder 3
- Faulty knock sensor or wiring
- Engine mechanical issue (e.g., worn piston, valve)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine knocking or pinging noise from cylinder 3
- Reduced engine performance and fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect knock sensor and wiring for damage or corrosion.
Step 3: Perform a fuel quality test and verify octane rating.
Step 4: Use a scope to monitor knock sensor signal and cylinder 3 waveform.
Step 5: Check for carbon buildup with a borescope and clean if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with active knock can cause severe engine damage. Have it diagnosed immediately.
How much does it cost to fix?▼
Costs range from $150 to $500 depending on the cause, such as replacing a knock sensor or cleaning carbon deposits.