Causes and Fixes P0301 Code: Cylinder 1 Engine Misfire

A P0301 error code is a misfire that means the number-1 spark plug is not firing correctly.

• Check Spark Plug Wires, Coil Pack, and Injector


The first thing to do is check all the most common parts for any physical or obvious damage.

Often the problem won’t be visible, but it is a good place to start; plus, it helps to know their location.

• Check the Spark Plug Wire


Look at the spark plug wire and be sure it is seated on the plug well.

Many mechanics will swap the spark plug with another one to see if the problem follows.

If the plug wires are swapped, be sure not to mix up the firing order, and take pictures if necessary.

• Check the Spark Plug


Remove the spark plug and see if it has build-up causing it to not be able to fire correctly.

Sometimes the spark plug will be old and need to be replaced.

Often, something else is causing the plug not to get power for a spark and will have a lot of build-up.

• Test the Fuel Injector

A bad Fuel Injector can also be a problem.

Again an easy way to check is to swap it out with a known good one and see if the problem follows

• Swap Parts with Working Cylinder.

A low-cost way to narrow down the problem is to swap out parts one at a time with a working cylinder.

For example, if cylinder two is working, swap the coil pack with one or three and see if the problem follows.

If the P0301 clears but a code P0302 comes up after the swap, you will know the coil pack is bad.

Summary
Fixing a P0301 is usually easy enough and falls in the backyard mechanic DIY category.

Of course, call a professional if in doubt.

The make and model of a vehicle will make a difference as some will be easier to work on than others.

Some cars and trucks will have parts that can be easily swapped, while others will be more difficult.

While it is best to find and replace the problem part if all the parts are old and the vehicle hard to work on, sometimes it is best to simply replace all new parts.