eric n

Coming back from Las Vegas today my car threw a p0303 and a 0300 error code. Ultimately misfire in cylinder #3 and random misfire. I was 100+ miles from home so I cleared the code and drove home normally. No incident. Now my car has a jlt cai and steeda tune, so warranty is out of the question.

Looking for any reasonable guidance. Thanks in advance.

As a note in Vegas I visited Exotics Racing AGAIN!!! I drove the 911 Turbo S on the track...... my freakin' God!!! If you get the chance, I highly recommend it.

eric n

As a quick note it happened right after filling up with some gasoline, which wasn't from a big name manufacturer. For what ever reason, I wasn't thrilled with this filling station. Could have been bad gas.

Twin Turbo

So your Mustang doesn't like you making nasty smells? Can't say as I blame it


Sorry, not very helpful. I guess just keep an eye on it for now and see if it throws another code. Other options could be the coil pack and/or spark plugs. Had a couple of UK owners that have experienced this recently.

Hope it was a one off though

eric n

I have seen both the plugs and coil pack as culprits on other sites, so replacing them will likely be the first move if this continues. Thanks for the insight.

14Glassback

With P303 I would take plug from that cylinder and swap it with another. Take coil and swap it with a different cylinder than what you put #3 plug in. May aid in diagnosis if next time the misfire registers on a cylinder you swapped parts with.