What is OBD-II Code P0307 – Cylinder 7 Misfire Detected

What is OBD-II Code P0307 – Cylinder 7 Misfire Detected?

Your car engine is a complex system that runs smoothly when all its parts work together efficiently. Any problem that arises during this process can lead to a loss in performance, fuel efficiency, or safety. An issue might arise that you cannot notice while driving but can be picked up by modern diagnostic tools, such as an OBD-II scanner.

An OBD-II scanner is a device that can connect to your vehicle’s onboard computer system and read any error or trouble codes stored there. One such code is P0307, indicating a misfire in cylinder seven.

In this article, we’ll explore what causes P0307 and how to repair the problem.

Causes of OBD-II Code P0307 – Cylinder 7 Misfire Detected

A misfire occurs when one or more cylinders in your engine fail to ignite fuel and air properly. In the case of P0307, cylinder seven is the culprit. The following factors may cause this issue:

1. Faulty ignition system: When the spark plug, ignition coil, or distributor cap fail, the engine cannot receive the spark necessary to combust the fuel-air mixture, leading to misfires.

2. Fuel delivery problems: If the fuel injectors or fuel pump have issues, the engine won’t receive adequate fuel, leading to misfires in one or more cylinders.

3. Vacuum leaks: Air leaks in the intake system can upset the fuel-air mixture ratio and cause misfires.

4. Mechanical problems: Issues such as worn camshafts or pistons, damaged valves, or crankshaft problems can cause a misfire.

5. Computer issues: Errors in the engine computer can lead to incorrect fuel-air mixture or other mechanical issues, leading to a misfire.

Repairing OBD-II Code P0307 – Cylinder 7 Misfire Detected

Once you’ve identified the cause of the misfire, you can begin the repair process. Depending on the issue’s severity, these are some of the common ways to repair P0307:

1. Replace spark plugs: Worn or fouled spark plugs can cause misfires, so replacing them can often solve the problem.

2. Replace ignition coils or distributor cap: When the coils or cap are worn or fail, they can cause a misfire. In such cases, you will need to replace the faulty component.

3. Replace fuel-related components: Faulty fuel injectors or a weak fuel pump can lead to misfires. Replacing the faulty components will fix the issue.

4. Repair vacuum leaks: Leaks in the intake system can cause misfires. Identifying and repairing the leak will remedy this issue.

5. Fix mechanical problems: Depending on the severity of the issue, some mechanical problems might need repairing or replacement.

6. Reset the engine computer: Sometimes the engine computer can detect false errors and cause misfires. Resetting it can often solve the issue.

Frequently Asked Questions

1. Can OBD-II Code P0307 harm my car?

Yes, misfires can cause damage to the engine, which can result in costly repairs. It can lead to overheating, engine shutdowns, and further inefficiencies.

2. Can I drive my car with OBD-II code P0307?

While it is possible to drive your car with the code, it is not advisable. A misfire can cause several issues, including performance degradation, fuel inefficiency, and damage to the engine.

3. Can P0307 affect fuel efficiency?

Yes, a misfire in cylinder seven can lead to lower fuel efficiency. This is because the engine is not getting the spark it needs, resulting in a decrease in performance and poor fuel economy.

4. Can a faulty oxygen sensor cause P0307?

Yes, a defective oxygen sensor can cause a misfire as it affects the fuel-air mixture ratio. These issues need to be fixed to remedy the problem.

5. How can I avoid OBD-II code P0307?

Regular maintenance and timely repairs are the best ways to prevent misfires. This includes replacing spark plugs, ignition coils, and fuel-related components when necessary, inspecting vacuum lines and intake systems, and ensuring your engine computer is functioning correctly.


OBD-II Code P0307 indicates a misfire in cylinder seven, which can cause problems for your car’s performance and fuel efficiency. By identifying the causes and understanding how to repair the issue, you can avoid further damage to your engine and enjoy a smoother ride. Regular maintenance and repairs are vital, so don’t hesitate to take your car to a professional mechanic when necessary.

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