How to Fix Error Code P0303? Cylinder 3 Misfire Detected

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Having the Check Engine Light come on your vehicle is annoying. Having a vehicle that is not running as it should and can be frustrating. We have written this article to allow you to educate yourself on error code P0303.

What Does Error Code P0303 Mean?

P0303 meaing

This issue will refer to the powertrain. However, there is no specific action that can be taken. You need to determine what to do with this code based on your make and model.

However, with this said, it does mean that there is an issue in the cylinder of the vehicle. In this instance, it is cylinder three that is misfiring.

What Causes a Misfire on Cylinder 3?

There are many reasons that a misfire may occur on cylinder 3. This could include your fuel system, ignition system, or engine failures. It is found that this code appears when the spark plugs are worn. You will also find this if the wires of the spark plug are faulty. Lastly, you may notice this if your ignition coil is faulty.

There are other ways that could cause the cylinder to misfire. This could include fuel injectors that are faulty, faulty O2 sensors, bad compression, exhaust valve has burned, or no fuel.

What are the Signs of Error Code P0303?

This is not something that will jump out at you. You will notice that your vehicle may start harder than it would normally. You may also see that it hesitates after starting. These are some of the initial things that would happen to your vehicle if it were misfiring on cylinder 3. You will know at this point that the vehicle is misfiring. However, you will not know what the error code is until you get a scanning tool. This will read you the error code.

How To Fix Error Code P0303?

There are elements in this that are complicated. We are not surprised if you decide to take your vehicle to a mechanic. Fixing this problem is something that involves special tools. You can do it at home. Just make sure that you have the code. If the code is P0303, continue reading.

  1. Make sure that the only code appearing is P0303. If there are other codes, they will also need to be addressed.
  2. Check your spark plugs and plug wires. You want to ensure that the plugs are providing the necessary spark. If it is not, it could cause a misfire.
  3. Make sure your wiring and connections leading to the cylinder are good. You want to ensure that all items are hooked up correctly. If you do not find issues with your wiring, continue reading.
  4. You will want to check your coil packs. These will wear down over time. Replacing these if necessary isn’t a terrible idea.
  5. If you have done everything on this list, you can now replace your catalytic converter. You can see if this is the case if your exhaust smells of rotten eggs.
    1. Do not inhale the fumes of your exhaust as the fumes are dangerous. You will notice the smell from a distance away.
  6. The last thing that can be looked at is the fuel injectors. If these are bad, replace them.

Keep in mind that your vehicle is damaged. Something is not working right. If you do not have the skills to do this job, you can take it to a mechanic. However, the problem is likely to spark plugs and wires.

What to Avoid

If you found that it is error code P0303, you likely will go to replacing everything but the plugs and wires. When you are fixing this error code, ensure you are replacing your spark plugs and wires. This is likely the problem. In most instances, this will be the reason you have this error code on your dash.

Do not go replacing all the expensive parts, be smart, analyze your plugs and wires. Ensure that you are diagnosing this problem properly.


Will a Bad Catalytic Converter Cause Error Code P0303?

It is possible that your Catalytic Converter is the problem. If you replace this, it could make the error go away. However, this could be an expensive fix. You may want to see if the spark plugs and wires are good first.

Is My Vehicle Safe to Drive with Error Code P0303?

If you are driving your vehicle with this error code, you should unplug your injector. This allows you to worry about the piston less. Plus, there are no other failures that could be the problem. It is not something that is going to make it unsafe to drive. However, it might be annoying.

You may notice that if you let this error persist, it will affect your speed. You will not have the acceleration power that you used to due to the misfire occurring on cylinder 3.

Wrapping Up

When you have this error code, it could be so many things. However, opt for spark plugs and wires. This may be the easiest way to solve the problem.

If this is not the problem, continue to follow our list of diagnostic measures. If you are not comfortable doing this job, there are many mechanic shops that will do it for you. It will cost you more when you take your vehicle to a mechanic shop.

Engine Misfire? Trouble Code P0303 Meaning, Diagnose Spark Plugs & Ignition Coils
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