Rear O2 Sensor - Fun Stuff

[Koko4]

I had a check engine light come on for a P0136, which is rear O2 sensor. I bought the correct one off of Amazon (Denso P/N 234-4154) and it came today. I sprayed the two nuts holding the O2 sensor on with PB Blaster before attempting to remove them (they're pretty dang rusty). The problem was when I tried to find the right size socket to get the bolts off. The bolts themselves look odd - they look as if someone had slightly rounded them off. However, I don't think this is the case, because I looked at both the front and rear O2 sensors and all four nuts looked the same. Does anyone know what size socket these nuts take? I tried 10mm, 11mm, 12mm with no luck. Is it a special type fastener? The last thing I wanted to do was to actually round something off, or try something "rigged" like using Vice Grips or something of the like. Thanks for the help.

The first time I had the code pop up, I reset it and it took around 1,800 miles for it to pop back on. Should I just leave it alone? I REALLY don't want to break a stud.

 

[MStudt]

I had a check engine light come on for a P0136, which is rear O2 sensor. I bought the correct one off of Amazon (Denso P/N 234-4154) and it came today. I sprayed the two nuts holding the O2 sensor on with PB Blaster before attempting to remove them (they're pretty dang rusty). The problem was when I tried to find the right size socket to get the bolts off. The bolts themselves look odd - they look as if someone had slightly rounded them off. However, I don't think this is the case, because I looked at both the front and rear O2 sensors and all four nuts looked the same. Does anyone know what size socket these nuts take? I tried 10mm, 11mm, 12mm with no luck. Is it a special type fastener? The last thing I wanted to do was to actually round something off, or try something "rigged" like using Vice Grips or something of the like. Thanks for the help.

The first time I had the code pop up, I reset it and it took around 1,800 miles for it to pop back on. Should I just leave it alone? I REALLY don't want to break a stud.

They're rust, so the normal 10mm won't work. Your best bet is to do what I just got done doing. Apply some heat from the torch to it for about a minute. You can try putting some locking pliers on the nut, and try breaking them loose that way. That didn't work for me, so I used some easy outs on it. These are what I ended up using, and they worked great.

 

[Koko4]

Wow, those are awesome! I've never seen anything like that before.

I read this thread: Changing Oxygen Sensor when nuts are rusted - YotaTech Forums

And found that people actually do end up using Vice Grips / propane to get these things off. It's crazy because I live in GA (and the 4Runner is from NC), so I never expected to see this amount of rust on those bolts. I might just leave this one alone until I get back from Texas.. I am actually leaving tomorrow to go on a 1,200 mile away work trip for two weeks, and IF I ran into problems it'd be better to have them happen when I get back..

My MPG's haven't seemed to suffer, though. Adjusted (for bigger tires) I am getting around 18-18.5mpg in the 3.4 V-6. Wish I had that 2.7 4cyl about now, though =/ Heard that swap is pretty much an all-or-nothing type, though: engine, t-case, tranny, exhaust, engine mount locations, fuel lines, ECU..I wonder if the current 6cyl wiring harness would accept it though. Off topic (sorry).

 

[MStudt]

Wow, those are awesome! I've never seen anything like that before.

I read this thread: Changing Oxygen Sensor when nuts are rusted - YotaTech Forums

And found that people actually do end up using Vice Grips / propane to get these things off. It's crazy because I live in GA (and the 4Runner is from NC), so I never expected to see this amount of rust on those bolts. I might just leave this one alone until I get back from Texas.. I am actually leaving tomorrow to go on a 1,200 mile away work trip for two weeks, and IF I ran into problems it'd be better to have them happen when I get back..

My MPG's haven't seemed to suffer, though. Adjusted (for bigger tires) I am getting around 18-18.5mpg in the 3.4 V-6. Wish I had that 2.7 4cyl about now, though =/ Heard that swap is pretty much an all-or-nothing type, though: engine, t-case, tranny, exhaust, engine mount locations, fuel lines, ECU..I wonder if the current 6cyl wiring harness would accept it though. Off topic (sorry).

What part of Texas are you going to? There's a big Toyota Jamboree in Gilmer next weekend.