I have a question about the O2 sensors on my 2001 f-150. I was just wondering if i could cut the cats out of it and put the O2 sensors back into the pipe or if i have to leave the cats on it? And if i did cut the cats out would there be any problems?

 

1st, you have theFederal/State/Canadian Govermentissue on removing a known good converter(s).
2nd, you have the ethical issue on removing a known good converter(s).
3rd, you have the issue with the OBDII not getting proper readings from the O2 sensors. There is one located up stream and down stream of the converter(s). This is to ensure proper operation on the converter(s), otherwise you're going to set a code.
4th, you need to provide more info with your questions.
5th, Why would or do you need to remove the converter(s)?

 

The sensors 'after cat' are actually catalystmonitors (efficiency).. If you rod/remove the cats it will most certainly trip a CEL..