What is P0301?
The diagnostic trouble code P0301 is defined as the “Cylinder 1 Misfire Detected” fault code.
It is a generic OBD-II trouble code triggered when your vehicle’s PCM (Powertrain Control Module) detects an engine misfire from your first cylinder.
When you have an active P0301 diagnostic trouble code, your vehicle’s Powertrain Control Module has detected a more than 2% increase or decrease in the camshaft’s revolutions per minute. This triggers your check engine light to come on.
If your check engine light is flashing on and off, the percentage increase or decrease in camshaft revolutions per minute is more than 10%.
In short, if you have a misfire in your engine cylinder 1, it reduces your crankshaft’s revolutions per minute, and your PCM will give you the P0301 diagnostic trouble code.
Every car engine has multiple cylinders, whether you own a Ford, Toyota, BMW, or Honda motor company vehicle. Cylinder number 1 in misfire code P0301 refers to the first cylinder in the firing order.
For example, V8 engines usually have cylinders numbered 1-4 on the passenger side and 5-8 on the driver’s side. V6s may have them labeled 1-3 on the front bank and 4-6 on the rear bank, depending on your engine design and manufacturer.
Note: The cylinders’ firing order doesn’t necessarily follow the numbering system, so make sure you know which cylinder is first in the firing order. You can consult your car owner’s manual or an online repair manual to find out.
However, P0301 only refers to an engine misfire problem in cylinder 1. Likewise, P0302 refers to a misfire problem in cylinder 2, P0303 to cylinder 3, and so on.