P0306: Cylinder 6 Misfire Detected
Can you still drive? Not recommended if the check engine light is flashing. Continuous misfires can overheat and destroy the catalytic converter. Drive only short distances to a repair facility.
What Does P0306 Mean?
Code P0306 indicates that the ECM has detected repeated misfires on cylinder 6. In a V6 engine, cylinder 6 is typically the rearmost cylinder on the passenger-side bank, making it sometimes harder to access for service. The misfire may be constant or intermittent depending on the underlying cause.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Worn or fouled spark plug on cylinder 6
- Failed ignition coil for cylinder 6
- Clogged or leaking fuel injector on cylinder 6
- Low compression from worn valve or piston ring
- Intake manifold gasket leak near cylinder 6
Symptoms
- Check engine light on or flashing
- Rough idle especially when engine is cold
- Engine vibration
- Reduced power and acceleration
- Possible backfiring
Diagnostic Steps
- 1Remove and inspect cylinder 6 spark plug for wear, fouling, or damage
- 2Swap ignition coil between cylinder 6 and a known-good cylinder
- 3Test fuel injector operation using a noid light
- 4Perform compression and leak-down tests on cylinder 6
- 5Check for intake manifold gasket leaks with a smoke test or propane enrichment
- 6Inspect spark plug boot or wire for carbon tracking
Recommended Parts & Tools
ignition coil
fuel injector
compression tester
leak-down tester
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $50 - $1200 |
| Parts Only (DIY) | $50 - $200 |
| Labor (1-3 hrs @ $100/hr) | $100 - $300 |
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Chat with AI About P0306Commonly Affected Vehicles
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Frequently Asked Questions
Why is cylinder 6 hard to access?
On many V6 engines, cylinder 6 is located at the rear of the engine near the firewall. This can make spark plug and coil replacement more difficult, sometimes requiring removal of the intake manifold on transverse-mounted engines.
Can a misfire damage my engine?
A misfire itself typically does not cause immediate engine damage, but unburned fuel entering the exhaust can overheat and melt the catalytic converter, which is an expensive repair. Prolonged misfires can also wash oil from cylinder walls.
Community Fix Reports
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