My sones rx8 keep going into limp mode. He has a park neutral switch code only. I thought the cat was stopped up and put a decat pipe on to solve the problem. It still goes into limp mode and niw got a lean code from the o2 sensor. I need some help.

 

I've only ever seen an 8 go into limp mode for two things ...... omp issue or maf plug not plugged in . I'm sure there are other ways it can happen but you should see a code for whatever the issue is and o2 sensor normally wouldn't cause limp mode.

 

Could be ignition system related or a vacuum leak. Did you reinstall both O2 sensors? What year is your car and is it auto or manual? What midpipe did you replace the cat with? When was the last time you changed out coils plugs and wires?

 

i doubt it is a true limp mode. Could be performance related issue and the system limits revs. I’ve had this happen before myself. If it was a true limp, the car would stay limiting revs at all times. He says it goes into “limp mode” meaning it probably works then limits revs while driving.

edit: found a helpful thread. Might have a bad front O2 sensor. Makes sense to me if you took the cat off and it was toast, it probably took the O2 sensor with it.
https://www.rx8club.com/series-i-tro...t-rear-192278/