Chevy Trailblazer P0301, Is the coil bad Here we have a Trailblazer that has a misfire and a P0301 code. I hooked a scanner to the Trailblazer and saw the misfire counter going wild on Cylinder number one. The P0301 code was set because of this misfire . If you had a code reader and saw the P0301 code you could do the same as i done here and move number one coil to a different location.If coil is bad it will then set a new code for the cylinder that is missing. Like a P0302 if moved to cylinder 2 or P0303 if moved to cylinder 3 Always remember also the plug wire or Boot can also be the cause of a misfire . A new coil fixed this miss in the Trailblazer.