Hello, We recently picked up a clean '99 S80 T6 sedan with 94K miles. Keep getting a code for misfire on cylinder #3 and car is noticeably not running on all 6. I replaced all of the spark plugs as my '96 850 is very sensitive to a bad plug but this helped only a little and did not fix the problem. Is it common to need to replace the coil pack above the plug or could it be another ignition problem? I have not had a compression test done and think it would be uncommon to have a dead cylinder in this car? Thanks!

 

Try swapping the coil with another cylinder and see if the code changes.
They go bad pretty often.