Do any of you guys have a detailed write up on how to replace the rear o2 on a evo 9?

 

Hit it with some pb blaster, or any penetrating oil of your choice, every 15 or so minutes to let it soak in for about 5 cycles. Then either use a long open ended wrench, a special o2 sensor socket with a long breaker bar, or clamp vise grips on there very tightly and smack the vise grips with a hammer. The wires go through the bottom of the car into the cabin under the front passenger seat. Look for a hole in the carpet. Unplugs rather easily. Install you can be more gentle with it because you aren't trying to brute force it free.

I don't remember if the plug will fit through the hole in the floor, but I got the sensor through the hole when I put my wideband in that location (because the plug on my wide band wouldn't fit). It did require a bit wiggling, but it worked.

 

yea pb blaster and 10 dollar o2 socket from any autoparts store

 

Also, be sure to hit the threads with anti-seize as it will make it a breeze the next time you take it off.

 

If you want to get rid of the rear O2 sensor altogether, you can also use ecuflash to simulate a rear O2 sensor. Check out these threads.

https://www.evolutionm.net/forums/5353216-post148.html

https://www.evolutionm.net/forums/6613499-post1.html

 

Yup that is the route I went(through tephra v7). No need for the check engine light to tell me that I don't have a cat, and especially waste the money on a replacement if it goes bad.

 

i read post on how to disable rear o2 but was a bit confusing!! my engine check light is on cause i don`t have catalitic converter. wha`t is the tephra v7 thing??? i red somthing about switching maps with it. tahnks

 

To use ecuflash, you'll need an openport cable. Tephra v7 is a patch to the Evo ECU that enable many features including alternate map switching. Take some time to read the stickied threads in the ecuflash section if you need more info on flashing your ecu.

 

Or if you don't want all the tephra v7 stuff, you can just patch the rear o2 delete/sim on your current rom...

 

There is a special O2 socket? Damn.
I bent my wrench cranking on that thing w/o PB blaster. When it came loose I really whacked my elbow too. So don't do what I did.

 

Yup.

 

thanks guys i have alrready bought the tactrix cable i hope it works on mu evo 9 gsr jdm. i am from uruguay south america and all the things take long time from buying them and having them here. is it dificut to put the tephra patch on the stock rom