A P0301 error code is a misfire that means the number-1 spark plug is not firing correctly.
Other P0300 errors point to other cylinders not working correctly.
For example, the P0302 code is spark plug-2 misfire, and P0303 would be spark plug-3.
If the cylinder is not firing correctly, the engine performance will be greatly reduced.
Causes of a P0301 Error Code
- Bad Spark Plug
- Spark Plug Wires
- Bad Coil
- Fuel Injector
Causes and Fixes P0301 Code: Cylinder 1 Engine Misfire
- Check Spark Plug Wires, Coil Pack, and Injector
- Check the Spark Plug Wire
- Check the Spark Plug
- Test the Fuel Injector
- Swap Parts with Working Cylinder.
- Symptoms of a Bad Idle Air Control Valve (IAC) - November 1, 2023
- How to Replace Headlight Bulb 2011–2020 Toyota Sienna - October 29, 2023
- Testing if a Fuel Pump is Bad Volkswagen Passat (1998 – 2005) - October 26, 2023
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.
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.
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.
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
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.
SummaryFixing 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.
