Cylinder 12 Misfire Detected
The P0312 code indicates that the engine control module (ECM) has detected a misfire in cylinder 12. A misfire occurs when the air-fuel mixture in the cylinder fails to ignite properly, causing a loss of power and increased emissions. This can be caused by issues with the ignition system, fuel delivery, or mechanical problems within the cylinder.
01. Most Common Causes
- Faulty spark plug or ignition coil on cylinder 12
- Fuel injector clogged or malfunctioning on cylinder 12
- Vacuum leak affecting cylinder 12
- Low compression in cylinder 12 due to worn piston rings or valves
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine running rough or misfiring
- Reduced power and acceleration
- Increased fuel consumption
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data to confirm P0312.
Step 2: Inspect spark plug and ignition coil on cylinder 12; swap with another cylinder to see if misfire follows.
Step 3: Check fuel injector on cylinder 12 for proper operation using a noid light or injector tester.
Step 4: Perform a compression test on cylinder 12 to check for mechanical issues.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with a misfire as it can cause damage to the catalytic converter and other engine components. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost varies depending on the cause. Replacing a spark plug or ignition coil can cost $50-$150, while fuel injector replacement may be $200-$400. Diagnostic fees are typically $100-$150.