I have a 1994 4runner with no cat. I need to replace my o2 sensor and have been told there are 2... one problem I can only find one, right under neath the driver. Is this the one I need to replace or is there one hidden further up where the pipes come together? I already bought the upstream o2 sensor just cant determine if the one under the driver is the right one

 

Federal and Canada emissions only had one. Cali had two.

 

Oooh, autozone told me there was two but I can't find a second one for the life of me. That helps a bunch thanx!

 

I would never listen to someone at Autozone lol. From the factory service manual:

 

Haha that helps now I know I'm not going to stick. $65 part in the wrong hole

 

I hope you didn't buy a Bosch O2. Denso and NGK only in these trucks.

 

um... yeah it's a Bosch. The old one is just going to stay on there and I will stick with my 12 mpg's. Just went to take it off, got ahold of the nuts with vice grips and they just crumbled. It is also rusted on there pretty good so I cant get it off even with what little nut there is left. I also have no idea what size nuts I needed and no money to take it into a shop to let them deal with it

 

Anybody know what size nuts I need?

 

Also, why not Bosch?

 

I can't remember why not Bosch... perhaps something to do with the signal switching frequency? I recall somebody might have said the signal oscillates a little slow, and the ECU doesn't like it. Fact of the matter is, they crap out much faster than the Denso/OEM parts.

As for nuts... I think they are 3/16s or 5/16s coarse thread (pretty small anyways. Definitely smaller than 3/8s). They tend to rust away just towards the end of the lifespan of the sensor, then you are supposed to crush them off vs trying to undo them. Luck, or Toyota engineering?

Trust me, get back to the parts store, get a Denso sensor (ya, more pricey... worth it) and grab 2 of both those sizes of bolts unless someone else chimes it. Please don't pay someone to swap it! It's easy!

 

I paid right around $65 for the bosch but I cound one made by denso I think on partsgeek.com for right around $60 with shipping, and yeah ill do it myself I was just a lil pissey

 

I hear that. It freaking sucks when something simple (lol 2 bolts) doesn't go as planned.

Ya get a Denso. You will be happy for 90000km (miles?)... er, a long time anyways.

 

Alright thanks a bunch for the help. I will take it back tomorow and buy a new denso along with a some new nuts. Good thing I work at a hardware store, ill just grab an assortment of nuts while I'm there tomorow

 

I DON'T know the exact nut size, but I think Toyota would have a pretty difficult time finding SAE nuts in Japan.

If you're going to pick up an assortment of nuts, I'd try a 10mm and an 8mm. Or think ahead, and get one of these http://www.harborfreight.com/6-inch-...per-47257.html (you'll use it ALL the time). Also: http://www.google.com/products/catal...d=0CNIBEPMCMAQ

 

This thread started picking up bad info fast.

 

maybe you had one after your cat, or where the cat should be. If so i would imagine there would be wires running somewhere around there where the sensor was cut out?

i have a 1990 pick up and no cat and all i can find is the 1 o2 sensor right before where the cat should be.

 

i heard that the bosch sensors were decent for fords... just not toyotas.
could this be true or did someone BS me?

 

Scope103: I know I really need to buy both of those, as I was trying to figure out what size nuts I need I was wondering why I didn't have those exact tools. I grabbed 8mm and 10mm and some random sae just to be sure.

B.stickwan: I looked for a second one and couldn't find it for the life of me so I just wanted to check and make sure there wasn't a hidden one between the block and where the pipes come together that I couldn't find or something

 

Well good luck to ya! I need to change my sensor too. I pulled up to a drive through window and the lady said my exhaust was burning her eyes haha. Runs a tad rich.

 

Hehe that's how mine is if I know I'm going to be sittin awhile I turn mine off or nose burns and my eyes are just about watering.