Started up my Daughter's car today (It has sat for about a week or so: home from school: has ran fine up until now) was misfiring badly and came up with code PO300. Ran it for about 10 miles or so and it cleared up. My daughter drove it tonight and the same thing occured.

Had the coil packs replaced per the recall about 6 months ago.....looking for ideas.

Thanks,

Rick

 

What kind of car is it? Mileage? Current on maintenance? We need more info then just the code.

Also, I have a 2000 S4, and got that code a few weeks ago. Ended up being a cracked vacuum line, which made my car run as if it was misfiring. Also, it could possibly be the mass airflow sensor. Try running the car with the MAF unplugged and see if it clears up. If so, then you may just need to clean it. After you clean it, plug it back up, and the car still runs bad, its most likely a vacuum leak.

 

The car is an 2003 A4 quatto. Has about 91K on it...everthing up to date. Cleaned the MAP sensor this morning....see what happens.