P0306: Cylinder 6 Misfire Detected

written by Edmunds.com^{This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.}
edited by Chase Bierenkoven^{Contributor
Chase Bierenkoven has been writing about cars in his head since he was a child. Now, he does it for real, covering automotive news and producing reviews for outlets like Edmunds, Forbes Wheels and CarBuzz. Chase's career as an automotive journalist began in 2020, and he has already written scores of road tests. Some favorites of Chase's include the Dodge Challenger 392, Mazda Miata, Kia EV6 and Bentley Bentayga. Outside his work with cars, Chase is often found justifying his latest broken German sports car to anyone that will listen or enjoying the outdoor spaces of his native Colorado.}
12/20/2024
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What does the P0306 error code mean?

The P0306 diagnostic trouble code indicates a "cylinder six misfire detected." Note this code is tied to a specific cylinder, and which cylinder is considered the sixth will depend on your car's make and model. This code is triggered when the engine control module detects combustion is not occurring properly in cylinder six. A misfire can have several causes and occurs when the air-fuel mixture in the cylinder fails to ignite or burns inefficiently, disrupting engine performance.

Why it's important to address the P0306 error code

A misfire in your engine can cause significant problems, including reduced fuel efficiency, increased emissions, and potentially severe damage to engine components. Prolonged operation without addressing the issue could lead to serious damage, such as catalytic converter failure or engine overheating, resulting in costly repairs.

Can I safely drive my car with this error code?

Driving with the P0306 code is not an option. While the vehicle may run, the risk of engine damage due to the misfire is simply too high. Continuing to drive it can exacerbate any symptoms and potentially cause extensive engine damage or failure.

Common symptoms of the P0306 error code

Illuminated check engine light
Engine running rough or vibrating
Reduced fuel efficiency
Noticeable power loss during acceleration
Hesitation or stumbling during throttle input
Possible engine misfire sounds (popping or backfiring)

How to diagnose the P0306 error code

Diagnosing the P0306 code typically involves:

Scan for codes: Use an OBD-II scanner to confirm the P0306 code and check for other related codes.
Inspect spark components: Examine the spark plug, ignition coil, and associated wiring on cylinder six for wear or damage.
Check fuel delivery systems: Verify that the fuel injector for cylinder six is functioning properly and not clogged.
Perform a compression test: Ensure cylinder six has sufficient compression to support normal combustion.
Inspect for vacuum leaks: Check for intake manifold or vacuum leaks near cylinder six.
Analyze live data: Use diagnostic tools to monitor misfire counts and real-time engine performance data.

How to repair the P0306 error code

Repairing the P0306 code may involve:

Replacing the spark plug and ignition coil for cylinder six.
Repairing or replacing damaged wiring or connectors in the ignition system.
Cleaning or replacing a clogged or malfunctioning fuel injector.
Addressing intake manifold or vacuum leaks near cylinder six.
Fixing internal engine issues, such as worn valves or piston rings, if low compression is detected.
Clearing the code and performing a test drive to confirm the repair's has been made.