Oxygen sensor help

[Atreyus]

So I replaced my front sensor with 234-4162 awhile back and looking to change my rear but wasn't sure what the part number would be. I used the URD site and it says 234-4153 is that the correct part? And also I know the front sensor helps with gas mileage, but what does the rear one do? I figure I'd change it out so I know everything is new and I can get the rear one pretty cheap Denso. Any help would be great!

 

[Bigmikelakers]

Did you have a hard time installing the front fuel sensor? Just bought the 234-9002 for my 01. Gonna put it in as soon as I get it.

 

[Atreyus]

It was fairly easy to do took about 15-30 mins.

 

[kball]

So I replaced my front sensor with 234-4162 awhile back and looking to change my rear but wasn't sure what the part number would be. I used the URD site and it says 234-4153 is that the correct part? And also I know the front sensor helps with gas mileage, but what does the rear one do? I figure I'd change it out so I know everything is new and I can get the rear one pretty cheap Denso. Any help would be great!

I'm sure the URD site gave you the right number. I was going to check Denso's site (www.densoaftermarket.com) but it seems to be down right now.

All the post cat sensor does is tell you if your cat is not working correctly. You don't really need to ever change it. Like you though, I changed mine just because I wanted a new one since I had no idea how old the one in there was.

 

[Nelsonmd]

yeah, just trust the URD list. It hasn't been wrong yet.

 

[Phx994Runner]

So just to confirm, there is only ONE front o2 Sensor on the 3rd-gens? My son's is a '99 and I'm sure it's the original one. He needs to get his plugs replaced as well, so I'll have him do both at the same time.

Looks like Amazon has it for $54:
Denso 234-4162 Oxygen Sensor (Air and Fuel Ratio Sensor)

Does anyone have a picture of where it's located?

Thanks!

 

[LittleCaesar]

Nope, it has two. One before the CC (cat converter), one after.

If you have a CA spec 4runner, it retains an A/F sensor in place of the pre CC O2 sensor.