My OBD II is showing a PO303, which is a cylinder three misfire. What would cause this?
1999 eclipse 2.4L auto

My OBD II is showing a PO303, which is a cylinder three misfire. What would cause this?
1999 eclipse 2.4L auto

First off, putting your make, model, year, and etc... in your signature makes things much easier for future threads you provide.

Second, this problem might be cause by a faulty Spark Plug or plug wire.
The problem might even be caused by a faulty 3rd cylinder injector, to do a quick but easy test to check to see if the injector is working grab something like a long screw driver and place the tip of it onto the injector itself while the car is running. Don't put the tip on the electrical connector but on the injector. You should hear a click sound when the injector "fires". Good luck.