I was here a few weeks ago and many of you helped out on my Grandson's car with P0042 code. Well CEL is on again but this time P0054 code. I did install a new Cat converter and 2 new oxygen sensors. However I bought the sensors on Amazon and from what I read about the code P0054 indicates resistance issues in the heated / post cat sensor. I have not looked fully at it yet but guessing maybe the new sensor is faulty. He did drive for over a week before the light came on again. I actually still have his old cat and sensors in the garage as I had not disposed of them yet. I think I may just swap sensors and see what happens first. I just went the route of both new sensors when I replaced the cat but maybe the old sensor is still good. I'll see this weekend. Any thoughts appreciated.

 

Bosch sensors?

 

There is no P0042 code. Guess you meant P0420 ?