I took it back and they stated it was now a P0420 code which was the catalyst and I needed to take it to Ford because it was under warranty mandated by the State. I took it to Ford, paid for another diagnostic test and was told they could not check the catalyst until "a leak at...
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...