Cylinder 8 Contribution/Balance Fault
The P0284 code indicates that the Engine Control Module (ECM) has detected a misfire or lack of power contribution from cylinder 8 compared to the other cylinders. This is determined by monitoring crankshaft speed variations and oxygen sensor feedback. The fault can be caused by issues with fuel delivery, ignition, or mechanical integrity of cylinder 8.
01. Most Common Causes
- Faulty fuel injector on cylinder 8
- Ignition coil or spark plug failure on cylinder 8
- Low compression in cylinder 8 due to worn rings or valves
- Vacuum leak or intake manifold gasket leak affecting cylinder 8
02. Symptoms You Will Notice
- Engine misfire or rough idle
- Check Engine Light illuminated
- Reduced engine power and fuel economy
- Engine vibration, especially at idle
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Perform a cylinder power balance test using a scan tool.
Step 3: Inspect spark plug and ignition coil on cylinder 8; 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 8 and compare to others.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause catalytic converter damage and reduced engine performance. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost varies depending on the cause. A simple spark plug replacement may cost $50-$150, while injector or coil replacement can be $150-$400. Major engine repairs can exceed $1000.