Just before reaching home as I was pulling off the highway, I noticed a rough sputter when my car was slowing. By the time I made it home, my vehicle had a rough idle, and threw codes p0027 and p0424, to top it off, there was hair coming out of the tailpipe. Later realized it was the insulation. Cleared the muffler, checked for any leaks, nothing. Started the vehicle and there wasn’t a rough idle or sputtering. Drove it around the block with obd2 connected. Ended up getting p0304 (cylinder 4 misfire) drove another 5 miles, and it threw the code one other time. Anyone run into this problem? Buying new plugs tomorrow, and testing ignition coils. The car is “new to me” 06 XC70 w/ 220k miles. It was running with absolutely no issues until today. Previous owner was the only owner prior to me. Any help would be appreciated

 

the P0027 is for the exhaust valve control solenoid (part of the VVT) either being slow to react or not working. The VVT is driven by oil pressure so you may have some luck cleaning the solenoid with carb cleaner or it may just need to be replaced. You may also want to consider an oil change and possibly a seafoam treatment and test for a clogged PCV. The P0424 is for the catalytic converter temperature which can be caused by an exhaust leak, fuel mix issue, rear O2 sensor etc. Considering you're getting a misfire code, I'd address the P0027 first and then check for air leaks in the intake or exhaust to see if this resolves on its own. Same goes for the misfires. You may also want to inspect the VVT hub as well to make sure there's no issues with the gear, the position sensor.

 

Thanks for all of the great info. After running tests on coil, turns out cylinder 4 coil shorted. Replaced the coil and all spark plugs, now it’s purring again. Unfortunately, the terrible gas mixture due to the bad coil caused all the other reads as far as emissions, and rattle free some of the inner lining inside of the exhaust.

replacing that soon, but overall I have a running vehicle again.