o2 sensor help. bank 1 sensor 1

I had the same code in my kid's 2000 2.7. Air fuel ratio sensor was stuck on a specific output (80 I think). Replacing the sensor fixed the problem. However, getting the sensor out was no easy task. Broke one of the studs and had to remove the CAT and have it drilled out. Be ready for this possibility and have alternate transpo lined up 'cause it might take a few days from start to finish.

 

is that the upstream sensor or the downstream sensor? I removed the upstream sensor yesterday with map gas and channel locks. (it was stripped when I bought the truck).

 

A/F ratio sensor is the upstream (closest to the engine and furthest from the muffler) sensor. Failed at about 160K miles.

 

Ok thanks.

so if this sensor fails it wont throw an o2 code, but rather the p0420 code?

I assumed it would throw an o2 code but I am curious what yours did.

 

true. they all have a finite life and 120~150~ thousand miles, these things are dying or dead
my 4runner 5vzfe a/f died at 130,000 (heater circuit) or so and the rear o2 at 142,000 (p0420) the p0420 code happened
ON april 20th no lies.

 

it will throws codes related to it's heater circuit (it has to get hot to work)
it will throws codes related to lean or rich

a/f (the front ones) typically throw a p11XX code

most common are these

https://parts.olathetoyota.com/p1135-code

https://parts.olathetoyota.com/p1155-code


but if the sensor is working, just 'off' you may get p0171 lean or p0172 (system too rich)
and the fun part is you get these a LOT when you use aftermarket sensors. Stick to toyota OEM
it's worth the bucks because it will always work. aftermarket is a crap shoot a lot of times.

 

Mine threw just the P0420 code. I initially thought it was the MAF sensor and so I replaced it shotgun style. Only when it didn't solve the issue did I get ahold of a data logger (I think it was called CRecorder) that revealed the sensor to be stuck and not producing vacillating voltage as it's supposed to.

 

Cool,

I am still unclear on how to diagnose the o2 sensors without the toyota factory part. I will need to re-read the manual as I think there is a test that uses volts off of the sensors while the truck is running.

 

Honestly, if everything else is tight and there are no exhaust leaks prior to the cat I would just spend the $100 and replace the a/f ratio sensor. Since your code references a lean condition and your truck has a lot of miles on it I would also replace the fuel filter. Have fun with that.

 

I went through similar codes last year and replaced my a/f sensor twice, so I have a spare Denso for a 2.7l. Problem turned out to be a bad connection, and I believe the spare is ok.

Got them from rock auto for around $110.

 

Thanks for that advice. I actually ordered the same one based on a few other similar experiences I read about.