A P0301 is one of a series of OBD-II error codes that are triggered when your vehicle’s computer has detected a “misfire.”
What exactly does this diagnostic code entail? Read on to learn more about what a P0301 means, what its symptoms are, and how you can diagnose and troubleshoot the problem.
What Does the P0301 Code Mean?
Diagnostic trouble code (DTC) P0301 stands for “ Cylinder 1 Misfire Detected.” This means that one of your engine cylinders is misfiring, specifically engine cylinder 1. All P030 + “x” codes—such as P0301, P0302, and so on—are misfire codes. The last number of the code tells you which particular cylinder is problematic.
A P0301 is a generic powertrain code, which means it can affect most vehicles and is not specific to any make or model.
What are the Possible Causes of the P0301 Code?
There is a multitude of potential causes for a P0301. Your car might be showing this trouble code due to any of the following reasons:
Ignition system problems, such as:
- A faulty worn spark plug
- A failed coil pack
- A bad spark plug wire (if equipped)
Fuel delivery issues, such as:
- A faulty fuel injector
- Wiring issues with the fuel injector circuit (e.g., loose connections, damaged wires)
- Problems with the powertrain control module, such as a damaged injector driver or outdated software (relatively rare)
Engine mechanical problems, such as:
- A leaking valve
- A worn piston ring or damaged cylinder walls
- A worn camshaft lobe or damaged lifter
- A leaking head gasket
It’s worth noting that if there are also misfire codes stored for other cylinders, the list of potential causes will be different. The diagnostic process may be different. But if you’ve only got code P0301 stored, you’ll want to start by focusing on issues that only affect cylinder number 1.
What are the Common Symptoms of the P0301 Code?
How can you tell if you’re dealing with a P0301? Even before you use an OBD-II scanner to check for trouble codes, there are a number of signs you can keep an eye out for that can alert you to the possibility of a P0301 or any similar error codes.
Here are some of the symptoms associated with a P0301:
- Rough idling
- Hard starting
- Car jerks from time to time, either while running or while idling
- Lack of power at acceleration
- Decreased fuel economy
- Check Engine Light
How to Diagnose the P0301Code
It can be difficult to diagnose and pinpoint the exact cause of most OBD-II codes due to the fact that they often have numerous possible causes. This is the same for code P0301.
To help you troubleshoot the code, check out the videos below:
How to Fix the P0301 Code
Unfortunately, there is no “magic bullet” fix for code P0301. This is due to the fact that there are a variety of possible causes, and there are different ways to fix the issue depending on the exact cause.
In most cases, you will have to replace the faulty part(s) that you’ve determined are related to the code, following a proper diagnosis.
And remember—all vehicles are different. When troubleshooting and repairing diagnostic trouble codes, make sure to consult the factory repair information for your application.
Repair manuals, such as those from Chilton, are useful, but an ALLDATA subscription is even better. ALLDATA has single-vehicle subscriptions for DIYers that provide detailed factory repair information.
Other Notes About Code P0301
Is it safe to drive with the P0301 code? Not necessarily. A misfire can cause additional damage to your vehicle, so you shouldn’t continue driving with a code P0301 set. You should address the issue immediately.