I have a 2005 Ford Taurus with only 54k miles on it. My check engine light came on and code P0300 came up and I was told I needed new spark plugs and wires. I had those replaced and the car ran terrible so I took it back. They informed me that they had crossed the coil wires...
For example, we had one 5-year old low-mileage Ford with the code P0420 that had been driven only for short trips. We cleared the code and drove the car on the highway in different modes and the code did not come back.2. Comparing the signals from the pre-cat air/fuel ratio (Fro...