Engine front o2 sensor

front o2 sensor

so i had my cel go off and my front sensor was bad so i finally got time to change it and it was exactaly like vamp said. which i was hoping it wasnt. its also a pain in the ass to get it off. i had to lay on the engine to get the bolts off. but like vamp showed in his install on his site the right bolt would not come off it just got crossed threated and would not come off. so i tried to cut it with a dremal, i have no idea how he cut them cuze i eventally realized that the whole stud was coming off. but with the stud off i still was not able to cut into it with out hitting the treads. so i just went to toyota and picked up a new stud. but all they had was a bigger one and i had to put some washers on it to fit. took me all day like 2 1/2 hours to compelete this job but it saves me from a machanic and speding crazy money. anyone else do this yet or was i just unlucky like vamp

only 2.5 hrs? lucky. replacing the front O2 sensor on my subaru took like 4 because it was rusted on.

humm nope never had a problem with the corolla. although once i wasn't using the proper tools since it wasn't available at the time and i gashed open a part of my hand which hurt like hell.

Yeesh

thats y i like my 7th gen it takes five min to change mine

yah so i thought the problem was fixed but i guess not and im really pissed off about it my cel went on again to work and i went to autozone to scan it hoping that it was just the sensor acting up because i didnt clear it with a scanner but just with the battery but nope. i cleared it hoping it would stay off and on my way back home like 25 miles later thing comes back on rrrrrrggggg the last code was a p0420 catalyst efficent below threshold bank 1 isnt that the freaking o2 sensor or is it the cat

also i was reading about another rolla that had a swap and they were having the same problem so i looked up the tsb for an 01 and i guess it was affecting all the corollas up 08 i think it might of been the same code do you think this is looking into

that would be a secondary 02 sensor code. It'll either be the 2nd o2 sensor which sits after the cat your catalyst converter has gone bad.

so is it worth it to replace the back one, those are a pain to do u need heat to get them out or should i take it to my machanic and see what he says. Also i found the whole cat system for like 180 but i didnt realize its the whole downtube and resonator in one. would it be easyier to get an aftermarket and have a muffler shop weld on a new one

well the thing is that's what the obd is telling us. You should do some additional diagnostics to narrow it down because these are both expensive repairs. And sometimes the malfunctions seems totally unrelated to the code.

so should i replace the other 02 sensor to see if that is the problem

that would be an expensive "diagnostic" approach.

I'm thinking its more than likely the cat.. or you could have a exhaust leak between the header and cat/rear o2 sensor.

If your state don't do emission testing i'd just install a cheap rear o2 sensor "cel fix" and call it a day.

A P0420 code could be triggered by a number of things. From what I've seen - very rarely does it actually relate to the O2 sensor (downstream - after cat) or the catalytic converter. Usually an issue with an exhaust leak, ECT sensor problem, even a wiring / ground issue. All that code says is the rear O2 sensor has a waveform that is unexpected - that "could be" an indication that the catalyst efficiency is low. Sometimes - these are ECM "glitches" - resetting the ECM gets rid of the code, in some cases - the P0420 CEL never comes back.

well i do have emissions so i have to fix the problem. but where is the most likely place for an exhaust leak and how would i test to see if it leaking. also the p0420 does keep coming up it lasted a lot longer when i removed the battery connector than if i used a scanner to clear the codes 2 days vs 25 miles but it still comes up. like i read b4 there was a tsb for the ecm of this car and many other toyotas for i think the 0420 code, so should i call toyota about it. and are things like that free or would i have to pay for them

Check the little donut gasket between the down pipe and the cat. Those tend to leak pretty often on the 8th gen rollas.

ok ill do that next day its nice out thanks for all the help everyone