Toyota Corolla 1,6vvti 2003 po505 and po420 ? Just passed couple of weeks ago emissions test and that makes me feel it’s not cat, like one mechanic says. Another says throttle body needs change. Another it’s lambda ???!!?? They all cost money and want to know someone with experience what might be it. Yesterday it was high idling and mechanic regulated it ( for now ) . Really want to know what to fix
And trouble code P0420 doesn't always mean the catalytic converter is BAD, just means it's operating under its threshold. So your cat is likely just fine since it just passed smog, it's hopefully just throwing a code since it's not running right with the IAC valve not working right.
Does it knock at all when it idles?
Thanks for the answer which sounds like my question. This is why I’m asking Scotty Killmer. I know it’s odd that it passed emissions test ( but that means for me that cat isn’t gone ?!) I was thinking that when throttle body isn’t working properly it gives the wrong information and signals to the computer and like this the whole evap system is working wrong ( lamda as well and that sends wrong fuel quantity figures ) I’m no mechanic just thinking logically and asking if that might be the ICU, needs change or regulating. Or is it the whole throttle body or cat or both.
I feel like it would be the throttle body and the cat because of the codes. Now those codes are for a idle air control valve and po420 is for the cat so that means the cat is bad, not too sure how it passed emissions