Hi everyone,
changed my up stream 02 sensor on my 4runner, now getting a MAF sensor check engine code, car runs like poo. Mechanic cleaned MAF sensor, but still no dice.
I was wondering if there was a relearn procedure? I ordered a new maf sensor, but unfortunately there is a shortage, and an oem one will take 1-2 weeks to get here. hopefully maybe there is a way to force a a relearn? apparently mechanic cleared the code and it came right back.

small side note, is possible for an 02 sensor to throw a maf sensor code? I gave my mechanic a denso sensor (which looked like a directly replacement) . was my mistake, I realize now how important an 02 sensor is in terms of fuel trims to leave it in the hands of aftermarket, but I'm just wondering did I put the ecm into a weird state by giving a almost good 02 sensor data reading, but not quiet right?

Thank you

Sorry I can’t help with your problem, but I will bump this back to the top to keep it visible so hopefully someone will have an answer. I’m particularly interested because I just recently purchased new front O2 sensors myself, but haven’t installed them yet because of my schedule. It is possible though that your new sensor may have been faulty. I have read about them just being bad right out of the box...

The front and rear sensors are different(before and after cat). I can't remember if the plugs are the same but make sure the correct one is used.

When you say car runs like poo what exactly to you mean? rpms surging and struggling getting up hill?

What do your Long term fuel trims look like?

in our year (2004) they were transitioning over to using AF sensors intead of 02 sensors, so might be a good idea to order it by the vin.

Ill post back once i figured it out, I found a relearning procedure on google . hopefully it applies to 4runners as well.

I dont have an obdII scanner, actually i lost my 15 dollar bluetooth one.

engine stalls, vibrates on hard accelerations.

I used the correct aftermarket denso part, I used the one for up stream for sure.

^^^^this^^^^

Yep, I got the the right one for the front. according to Denso's site, and it matches the old one that came out. So it was definitely not an Air fuel sensor.

Relearn trick didn't work.

Can you get to an Autozone and get them to read for codes? Its free.

Sounds like you might have a misfire - plugs leads got interchanged and the firing order is wrong?

Hmm... I hope I have the correct front sensors. I looked them up on the Denso site to get the exact part numbers, but ended up ordering them from Amazon, since they were cheaper, and had free prime shipping. I was not aware of that transition you mentioned, and there was no notes about that on the Denso site, so I just went by the application to get the part numbers.