Figuring out why your Check Engine Light is on means deciphering OBD-II (or “OBD2”) codes, and that can be kind of annoying. That’s why Car Bibles did it for you! You’re welcome, now let’s get into solving your issue.

OBD2 P0301: What It Means

This code indicates that cylinder 1 is experiencing a misfire. It’s good that it’s specific, that helps narrow things down and makes trouble-shooting a bit easier! A quick scan of the OBD-II system via a code scanner will reveal this and get you well on the way to remedying it.

Likely Symptoms 

Here’s what you may experience due to P0301 code:

  • The Check Engine Light is on or flashing. This is the first thing that will happen with this code: That unmistakeable light will be on, or flashing in your face.
  • The engine is running rough or stumbling. The engine will run a bit rough, stumble a bit, and generally not feel healthy.
  • There’s a fuel smell in the exhaust. You can smell a pronounced hint of fuel, no matter the car being cold or fully warmed up.
  • The car seems to be a little weak. As the ol’ country song goes, well the ol’ grey mare she ain’t what she used to be. But in this case, it’s temporary and can be fixed.

Probable Causes

Here’s what could be causing the issue:

  • The spark plug, spark plug wire, coil, or coil pack could be faulty. Since this code pinpoints that cylinder 1 is misfiring, inspect this cylinders ignition components. Check your owners manual or a service manual to determine which cylinder is cylinder 1.
  • The injector could be on the fritz. The injector isn’t spraying an adequate or constant amount of fuel; it could be clogged, inoperable, leaking, etc.
  • The camshaft sensor and/or crankshaft sensor might need replacing. These sensors might not be sending signals to the car’s PCM, making it do a little guessing as to how to keep the engine running properly. This is significantly more rare and usually associated with other codes.

What Part Is Potentially Affected?

Essentially, everything associated with getting cylinder 1 to operate properly. It should also be said that there could be carbon build-up on the intake valve or valves, if its a direct-injection car.

Possible Fixes

Here are the most common fixes to remedy P0301 code:

  • Replace the spark plug, spark plug wire, coil pack or coil. Inspect them, and if the spark plug looks like its completely burned out, that’s the cheapest fix. Then plug wire, but it’ll be hard to judge if the wire looks to be in good condition. A good way to diagnose the wire and coil pack are to swap them with another cylinder’s; if a re-scan then reports that the misfire has jumped to a different cylinder, that helps narrow things down. Just make sure you don’t confuse the order of wires before you go un-plugging!
  • Replace the fuel injector. If the ignition bits are good or have been replaced, and a code is still showing up, inspect and replace that cylinder’s injector. But before doing so, on direct-injection cars, inspect the intake valves to ensure there isn’t a bunch of carbon buildup, raining on the engine’s efficiency parade.
  • Replace the camshaft position and crankshaft position sensors. These can get pricy, and they’re also rarely the cause, so make them last on the list. A multi-meter can be used to find out if they’re sending signals and aren’t dead.

Finding The Parts You Need

Now that you’ve figured out what’s wrong with your hooptie, let’s talk about where you’re gonna find that part’s replacement.

There are plenty of places you can buy auto parts from, but Car Bibles gets paid if you click this Advance Auto link so that’s the one we’re serving up. Advance Auto Parts also has delivery, curbside pickup, and a host of helpful diagrams to aid your repair!