Cylinder 12 Contribution/Range Fault
P0296 indicates that the Engine Control Module (ECM) has detected a lack of contribution from cylinder 12, meaning the cylinder is not producing enough power compared to others. This can be caused by fuel delivery issues, ignition problems, or mechanical faults such as low compression. The ECM monitors crankshaft acceleration and misfire counts to identify the weak cylinder.
1. Most Common Causes
- Faulty fuel injector on cylinder 12
- Ignition coil or spark plug failure on cylinder 12
- Low compression in cylinder 12 due to worn rings or valves
- Vacuum leak or intake manifold gasket leak affecting cylinder 12
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle
- Reduced power and acceleration
- Poor fuel economy
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Perform a cylinder contribution test using a scan tool to confirm cylinder 12 is weak.
Step 3: Inspect spark plug and ignition coil on cylinder 12; swap with another cylinder to see if misfire follows.
Step 4: Check fuel injector pulse and resistance; perform a fuel injector balance test.
Step 5: Perform a compression test on cylinder 12 and compare to others.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the misfire can damage the catalytic converter and cause further engine damage. Limp home or tow to a shop.
How much does it cost to fix?▼
Costs vary from $150 for a spark plug/coil to $500+ for injector replacement or compression repairs.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.