The illumination of the Check Engine Light is common due to ignition misfire, often caused by bad spark plugs or ignition coil.
Average mileage: 144,400 (141,200–150,000)
8 people reported this problem
My Crown Vic started running rough and idling loudly. First I replaced all of the spark plugs and that helped for about a year until it started happening again. This time it would run very rough when accelerating and I was getting very bad gas mileage. It also threw a check engine light that was a #8 misfire. I ended up replacing all of the spark plug wires and boots. It is now running like a dream.