I have a 1995 toyota 4runner v6 4x4. How many o2 sensors do I have and does anyone know the part numbers Thank you in advance for your help.

 

Your emissions sticker, located on the hood, will tell you (IIRC) if you have a california emissions system or not. If you have cali emissions you have two, if not you have only one. You can look under the truck also, catilytic converter is nearest the engine and muffler farther from engine, there will be one place infront of and possibly another behind the CAT.

You can input the VIN at one of the online parts shops and it'll likely tell you if you have one or two aswell as the OEM part number.

Pretty sure most/all denso four wire sensors are interchangeable.

 

Even if truck has two, only really need the one before the cat. Even if the second O2 goes out it will not throw a code and will not affect performance. You can find the correct O2 at sparkplugs.com, then shop around for best price. Make sure you buy a direct fit Denso sensor. Don't waste your money on anything else.

 

Try Denso 234-4052. I bought this same sensor off eBay for $30.00 about two months ago. Good luck!

 

Thanks for all the help guys. This place is great

 

According to RockAuto, the Denso 234-4052 is only for the NON-California 1992-95 pickup/4runner. For the California model, the Denso number for the downstream sensor is 234-4154.

(It also matters whether you have a dually, which I've never seen. Toyota shows 4 different part numbers for the Sensor, depending on Cali/not upstream/downstream.)

So Denso and Toyota, at least, say the 4-wire O2 Sensors are NOT interchangeable.

While I've never disconnected my downstream sensor to check, I would expect that a disconnected downstream sensor SHOULD throw a code 27.

 

I have an upstream before cat but non after cat there is the plug there for one but nothing connected but no where on pipe for it. I am getting terrible gas mileage right now and check engine light is on but no one seems to be able to read an obd1. I wonder if when he replaced the exhaust he didn't fit the one after the cat on there.

 

My 88 3VZ (California emissions equipped) only has one O2 sensor BEFORE the cat... Yours SHOULD be the same

I don't mean to thread hijack , but can someone post the part number for a cali-emissions equipped 88 4runner w/ the 3vze? Thanks!

 

According to Denso, 234-4052 is for both Cali and non-Cali upstream. Denso doesn't list a 234-4154 as being available for the truck.

http://www.densoaftermarket.com/cata....php?part=o2sn

 

http://www.4crawler.com/4x4/CheapTri...CheckConnector
http://www.4crawler.com/4x4/CheapTri...es/index.shtml

 

ECU will throw a code for 2nd o2 sensor malfunction, my brothers 93 had to have sensor replaced to clear check engine light and pass emissions test.

 

Learned something new then. A malfunctioning upstream rarely throws a code, so I am surprised. I don't have a Cali truck, and being in Alabama, I have never personally seen one. I based my assumption off everything I had read.

 

Codes 27 and 71 are California specific so I'm not surprised you've not heard of them. I wish I hadn't California emissions are a pain.

 

My error; I was looking under 1995 truck. Which is usually the same. Another lesson for me to be careful about assumptions.

 

71 Isn't as california specific as you might be led to believe. If you have an EGR temp sensor you'll get this code. Mine is definately not cali spec, been here done this one.

 

Pardon me while I ramble.

This is slightly better than the primary o2 sensor code, it tells you when primary reads rich the 2nd lean, but only triggers at full throttle aka useless unless you do it specificly to test if the primary is reading correctly.

And of course I have to "whine" about the test proceedure, OMG I thought the EGR test was bad. code 27 takes over 20minutes at 50+
Good luck doing that in your average metro city..

 

How do you have an egr temp sensor? The 93 FSM says this is Cali only. Did this change for 94?

 

Not sure if or when it might of changed, it's pretty easy to spot located at the back of the air chamber where the egr is plumbed in.

 

I believe the purpose of code 27 is to tell you that the Catalytic Convertor is no longer working. The O2 content downstream of the cat should not be swinging the same way as the content of the upstream.

I see the same note in the 1993 manual, but both RockAuto and ToyotaPartsZone call out 89412-50010 without "California Spec," and applying 1993.08 to 1995.11

August 1993 is pretty late in the 1993 model year, so it could well have been added after the FSM was written.

 

Very interesting. My 93 non-Cali does not have the sensor.