How To Fix P0301 Trouble Code and Clear the Check Engine Light

Diagnostic trouble code (DTC) P0301 is caused by a misfire on cylinder 1. This code is typically caused by a faulty spark plug or bad wiring connection to the cylinder, and a quick visual inspection is usually all it takes to solve the problem.

However, there are many other reasons why P0301 might show up, as a vacuum leak or failing catalytic converter can cause your engine to misfire as well. It’s important you diagnose the problem properly so you don’t end up throwing money at the car.

This infographic covers everything we know about P0301, such as any symptoms you may or not notice. For some, a check engine light is the only symptom, and the vehicle runs just fine. In many cases like this, you can just clear the code and it will never return.

However, if the code comes back, it’s important to check out what’s going on with your engine. A misfire can cause internal engine damage and shorten the life of your vehicle. Here are the symptoms, causes and solutions for fixing P0301…


  • Check engine light
  • Vehicle is hard to start or has difficulty starting
  • Rumbling or stalling from the engine


  • Bad spark plug
  • Poor connection to spark plug – check the spark plug wires, or connection to coil packs depending on your vehicle.
  • Distributor cap not working properly
  • Vacuum leak
  • Failed catalytic converter
  • Faulty or dirty fuel injectors
  • Dirty or faulty MAF sensor – an improper air reading will cause the wrong air/fuel ratio and eventually a misfire

How To Fix P0301 Trouble Code
Infographic Source: 

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