I spent the day chasing down a tricky problem. I had a flashing check engine, rough running, and P0301, 0304, 0305, 0307, 0308, 1313, 1314, 1316.

I was looking for common issues like fuel, common wires, CKP, throttle body, MAFS, multiple valve cover seal leaks that might cause multiple misfires; all to no avail.

Then I noticed when I reset the codes that P0305 (cylinder 5 misfire) always came up first, then the others would eventially follow. I moved the number 5 coil to cylinder 3 and then P0303 would come up first. I moved this coil to cylinder 2 and then P0302 would come up first.

I replaced this coil and all is perfect.

So the conclusion is that in some failure modes, one bad coil can cause multiple misfires!