P0306 Code: How To Fix Cylinder 6 Misfire [Cause & Location] (2024)

The OBD-II codes are created to point to a specific problem with a car. If you notice problems with the engine, and the check engine light turns on, the first thing you should do is to check the car with the OBD-II scanner. If after the scanning you get the P0306 code, the first thing is to understand what it means.

The P0306 error code shows that there is a misfiring problem with the sixth cylinder in the engine. The car moves when the fuel is burned and after the power is generated inside the cylinder. The pistons generate power when they are moving up and down in the cylinder, while the fuel is ignited with a spark at specific times. An engine misfires when the timing of the ignition is off.

The P0306 error code can happen for a whole array of reasons, and it can be difficult to diagnose. This error is considered to be very dangerous. You should stop driving the vehicle immediately. Stay with us to learn all about the symptoms, diagnostics, and ways to resolve this issue.

The Anatomy of the P0306 OBD2 Code

Knowing how the engine works, and what is the combustion will help you to understand the problem. The P0306 error code is a complex one and can be a result of several engine systems faults.

What Does P0306 Code Really Mean?

The P0306 code can point to several different problems in the engine. This issue is usually caused by a problem in the ignition system or a fuel delivery problem. Sometimes the issue is with the EGR system. Since these systems are complex we will focus parts that are usually the problem:

• Faulty, worn, or damaged spark plug. If the spark plug is damaged or not working properly the cylinder can stop firing. If the spark plug is damaged it can send an ignition spark to the ground
• Damaged or clogged fuel injector. If the fuel injector is not delivering enough fuel, that will result in low fuel pressure. In those conditions the cylinder frequently misfires
• Low compression in the cylinder. If the valves or rings inside the cylinder are faulty that will cause low compression. When there is low compression in the cylinder that will lead to the cylinder misfiring
• Leaky valves. If the oil is leaking from the valve cover into the cylinder, that can cause a short to the spark plug ignition
• Problem with the EGR. If the EGR is stuck in an open position it can cause a misfire
• Other mechanical problems with the engine. Those include a leaking head gasket, distributor failure, a vacuum leak, or a defective crankshaft position sensor.

Sneaky Causes a P0306 Code

There are several sneaky causes for a P0306 code, that are not always connected with this problem.

• A bad Mass Air Fuel (MAF) sensor. This sensor is responsible for calculating the amount of air that enters the engine. If the filter is bad or clogged, it will not calculate the proper amount of air. That will result in the engine running rich in fuel.
• Old or dirty fuel. If the fuel is old or contaminated it doesn’t have the same characteristics and features of freshly added fuel. That can easily lead to a problem with misfiring.
• The timing belt or chain skipped a tooth. That can lead the engine to work unevenly causing a misfire.

See Also: P1450 Code: Unable To Bleed Up Fuel Tank Vacuum

Possible Warnings: Symptoms of a P0306 Code

Several problems can be a sign of a problem with a misfiring cylinder and in this case the number 6 cylinder.

• Check engine light is turned on
• Rough idling
• The engine has problems when accelerating, like hesitation and rough work
• Sometimes the smell of gas is stronger than it should
• A sudden drop in fuel economy

There are cases when no obvious symptoms can signal the driver that there is a problem. But, usually, the check engine light will turn on.

Diving Deeper into the P0306 Code

To be able to fully understand the P00306 code, you need to understand the combustion process. It is also good to know the basic parts, and how they work. This can help in different problematic situations regarding the engine.

The Technical Side of P0306 Code

The most common culprit for this problem is the ignition spark timing. The powertrain control module (PCM) is using information from the crankshaft and the camshaft position sensors, and the throttle position sensor to time the ignition spark properly.

The crankshaft is moving almost twice as fast as the camshaft. The PCM needs to know the location of both of the components. Both a general location and a location concerning those components. When the camshaft, the crankshaft, and the piston align, then the valve is open. That is known as a compression stroke.

During the compression stroke, the air and fuel are drawn into the combustion chamber. Now the ignition spark is needed to cause the combustion process. The PCM identifies the location of the crankshaft and the camshaft. It sends a voltage signal that incites the spark from the ignition coil. The spark goes to the intake manifold or the cylinder head and creates a controlled explosion.

If the explosion doesn’t happen, that will impact the engine’s RPMs. The PCM will detect this and will monitor the position of the camshaft, the crankshaft, and the coil voltage inputs. With the information, the PCM detects which cylinder failed to misfire. Then it will show an error code message.

How the P0306 Code Affects Your Engine

The driver will at first notice a check engine light on the dashboard. Depending on the case, the effects on the drive can be different. The most common problem that drivers identify is poor engine performance. Those include problems with acceleration and rough work at idle. Drivers also notice poor fuel economy as a frequent result of a P0306 code.

If the problem is not fixed soon, engine damage can be massive. If the driver decides to ignore the error code that can result in ignition failure and catalytic converter damage. That can also follow with other engine-related issues.

Practical Solutions for P0306 Code

Depending on your mechanical knowledge and experience, you can conduct diagnostics and repair. The inspection should start with more obvious components. From there move to those less susceptible parts.

DIY Fixes for the P0306 Code

1. Do a visual inspection of the spark plugs. In case they are worn, old, or damaged, replace them. Ideally, change them all at once. You can also remove the spark plug from the sixth cylinder and replace it with another spark plug. Run a diagnostic scan and see has anything changed
2. Check for vacuum leaks. For this, you will need a vacuum tester gauge, a carb cleaner, and a propane torch
3. Inspect the fuel injector of the sixth cylinder. To do this you will need to complete a leakdown test. This way you will check for problems with the intake and exhaust valves, piston rings, head gasket, and cracked cylinder head. For this, you will need some professional tools like a source of compressed air and a leak-down gauge kit. Also get some basic hand tools, spark plug sockets, the vehicle instruction manual, and paper to write results.

If you find this overwhelming, you need to contact a mechanic. They know the exact vehicle diagnostic process for this problem.

Check Out How to Fix Error Code P0306:

Professional Solutions to P0306 Code Issues

The approach of a mechanic to diagnose this issue is similar:

1. First, they will do an OBD-II scan to check for errors. If they notice any other codes, they will address them first. They will do a freeze frame and check the exact conditions in which the misfire happened. Then they will clear the codes and do a short test drive of the car
2. If the error comes back the mechanic will check the wiring and the connectors of the spark plug and the ignition coil. Sometimes the plug wire can leak the ignition spark into the ground
3. They will move the spark plug to the other cylinder. That way the mechanic can check will the misfire move with the spark plug. If that happens, then the problem is in the faulty ignition coil or the faulty spark plug. The only way to resolve it is to replace it altogether
4. Next in line for the inspection is the fuel system. The mechanic will check does the engine gets enough fuel. Low fuel pressure can cause misfiring. They will check the fuel injection for any blockage or clogging. They will also check the fuel injector wiring and connector
5. If nothing helps, the mechanic will conduct leak-down and compression tests. The tests will identify any mechanical problems causing the misfiring.

See Also: P0430 Code: Fixing Catalyst System Efficiency Below Threshold Bank 2 Problem

Preventing Future P0306 Code Triggers

Taking care of your car is the only way to keep it operating properly. That includes regular maintenance, following the user manual, and visual inspection of the engine.

Regular Maintenance to Prevent P0306 Code

Proper maintenance and regular service inspections are the best way to prevent the P0306 code from reappearing in the future. You should change the spark plugs at the correct time intervals. Also, the mechanic should visually check the integral parts of the engine whenever filters and oil are changed.

Proactive Measures Against P0306 Code

If you notice any symptoms like stalling, rough idling, or engine hesitation, pay a visit to the mechanic. Talk about the symptoms you noticed. The mechanic will check the components that could be faulty. This way you will prevent further problems with cylinders misfiring.

FAQs about P0306 Code

Need More Help With A P0306 Code?

The OBD-II system can signal dozens of different problems. Some are less serious, and you don’t need to worry about them immediately. But, some error codes, like engine code P0306 demand your full and undivided attention. Driving with this error can destroy your engine. Even if you didn’t notice any significant symptoms, that doesn’t mean that the problem is minor.

If you don’t have the knowledge or experience, contact a mechanic. Get your car checked. A simple thing like a defective spark plug can cause so many expensive issues. Once you resolve the issues, keep your car in check. Maintain it properly. That is the best way to keep this type of problem away.