If you get Ivan’s reflash, no. If you don’t, yes - otherwise you’ll get an error code flashing up. It’ll also affect low RPM running (when the O2 sensor is needed for closed-loop running. At least, I think that’s the right way round!!) :grin2:Thanks for all the Info. Do I have to put the O2 sensor back on? What would it do if I didn't install it back on? thank you