Car Engine

What Causes An Engine To Misfire And What Should We Do?

Mike Cross
Updated May 18, 2021
What causes an engine to misfire

Engine misfires are no joke. Repeated happenings are a sign that major maintenance may be needed, and it is important to get this issue checked out right away.

Lucky for you, we’ve got a number of tips here because you likely need an answer fast. Good job on getting off the road and doing research, but now let’s get you back on the road. Engine misfires happen for a number of reasons. Let’s take a look at what causes an engine to misfire.

What causes an engine to misfire?

What Causes an Engine To Misfire?

This may result from something like a catalytic convertor that needs changing. If this is true, your car will emit higher emissions as the carbon monoxide isn’t properly converted to carbon dioxide, which can also cause the vehicle to run at higher temperatures and put extra wear on the engine. Both this and problems with the spark plugs or wires are easily fixed by a mechanic.

Engine misfires often start with just one instance. Maybe you get the problem looked at and get a light fix, or maybe it was a simple glug in the fuel line that backed up the flow, and the issue will fix itself. We caution any drivers who experience a misfire to have the engine looked at by a professional. In most cases, it won’t be the end of the world but it’s better to be safe than sorry.

There are three basic categories of engine misfires:

  • Faulty engine (the worst category). If you have a faulty engine, you may be in trouble and need significant help. These issues are rarer than the other two categories, especially in newer vehicles. But if you’ve had multiple engine misfires and everything else about the car seems to be running correctly, get the vehicle into a mechanic ASAP.
  • Faulty engines may eventually seize, essentially ruining the car until you get a new or rebuilt engine in there. These issues stem from mechanical errors, lack of changing the oil when needed, or shoddy connections between parts and the engine. This is the biggest reason why it is important to get your car checked out right away before it gets any worse.
  • Ignition, spark plugs. Your spark plugs may be worn out, or there may be a problem with the ignition line. Try to note what happened when you attempted to start the car before the engine misfire. Did you notice a problem right away, such as an abnormal noise or vibration, prior to the misfire? The problem may fall into this category if that is the case.
  • Gas-related. Sometimes the gas flow into the engine is insignificant. Again, this is something that should be brought to the attention of a mechanic as soon as possible. It can be fixed pretty quickly in most situations.

Emissions Tests

What causes an engine to misfire

If you live in an area that requires emissions tests, you will likely fail if the engine misfires or if there is a problem with the catalytic convertor. When it is clogged, the car is emitting dirtier fumes at a much higher rate.

You will notice severely decreased acceleration when the catalytic converter is failing. It shouldn’t fail if other engine maintenance is maintained, most problems with this part are a result of other issues not being taken care of promptly.

This is a big reason to keep up on other engine-related maintenance – the last thing anyone wants is a stalled engine and a failed emissions test.

Is it Safe To Drive With a Misfiring Engine?

Absolutely not. In worst case scenarios, your engine will stall and be completely ruined. If your check engine light is on, it is important to go to a mechanic immediately. Another option is to pull into an auto parts chain store and have them run a test – most have a little machine that they bring out to the parking lot. It will run a test on the engine to see what is wrong, and can turn off the light if there is not a problem.

If your engine is misfiring or the check engine light is on and you can’t figure out what is wrong with it, consider taking these steps:

  • Change the Oil. As simple as it sounds, many people do a terrible job of keeping up on oil changes. There is no dumber way to ruin your car’s lifespan and performance than by not following recommendations on oil changes. They are cheap, quick, and with a little learning, the effort can be done at home in your garage. Use the correct type of oil (i.e. 10w30, 5w30 and 5w20, etc.). The magnet sticker on the inside of your windshield from the previous oil change will often note which kind to use, or check the car’s manual.
  • Check the O2 sensor. It might be worn out and in need of replacement. The oxygen sensor calculates the amount of air in a vehicle’s exhaust system, and if it isn’t working correctly the engine won’t perform as well as it should and you’ll burn through fuel much faster. Worn out sensors can damage other engine parts such as spark plugs and the catalytic convertor. Your fuel economy will decrease by up to 40% if this happens to you.
  • Using a scanner to find error. Most cars have 2-4 O2 sensors. Using a bluetooth obd2 scanner will tell you which one needs replacing. Your car’s manual should detail how to change them, and all you need to do is unclip the old one and clip on the new one.


What causes an engine to misfire is all about the mechanics under the hood, and how old the car is.

If you (and any previous owners) have taken good care of the vehicle, any misfiring should be something small that can be fixed. Hopefully, this is a one-time thing that doesn’t turn into a trend.

If you found this article to be informative, please share on your social channels so that others can learn as well. Who knows – you might save someone a major headache down the line!

We love to hear about unique circumstances related to cars. If you’ve got a story, share it in the comments down below.

Most cars have 2-4 O2 sensors. Using an obd2 scanner will tell you which one needs replacing. Your car’s manual should detail how to change them, and all you need to do is unclip the old one and clip on the new one.

Mike Cross
Life is too short to drive with stock audio

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One comment on “What Causes An Engine To Misfire And What Should We Do?”

  1. I appreciate the information given in this article regarding the possible causes behind the engine misfire. Deformities in the spark plug could also be responsible for the engine misfire. The spark plug loses its ability to generate the ignition required to start the internal combustion. Any signs which indicate that the spark plug has some complications should not be ignored. The reason behind the appearance of such deformities should be identified and repaired immediately.

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