Did I get the wrong 02 sensor?

[Mudeprived]

I ordered two 02 sensors for my 99:

234-4153

234-4162


The 234-4153 is the downstream 02 if I am correct the 234-4162 is upstream. However, the upstream sensor has a slightly different plug than the OEM sensor that just came off the truck.

Left is Denso, right is Toyota.

I am guessing I got the wrong upstream sensor?

The new Denso downstream sensor has the same plug as new upstream sensor and plugs right in where it should.

 

[TheDurk]

You either bought the sensor for a Cali. type and you have a Federal, or vice versa. If the upstream is different from the downstream, that means it is a Cali. A/F sensor. The O2 sensors all have the same plug, whether upstream or downstream.

 

[tystaco]

I just did my federal emissions 2000 Limited front O2 sensor and it was 234-4162...I also ordered the 234-4153 based on a review on Amazon that said for 4runners you needed a longer tail for the downstream 02....but I returned 234-4153 because my two 02 sensors, from the factory, had the same length pigtail.... Long story short, I had no issue with 234-4162 on a federal emissions...if yours is Cali, I agree with the post above.

 

[Mudeprived]

I am in PA and I bought this truck in PA. It's been in PA since day 1.

Amazon is saying this is not compatible with my 1999 Toyota 4runner but I swear it said it was compatible when I purchased it.

https://www.amazon.com/Denso-234-41...=UTF8&qid=1503523198&sr=8-3&keywords=234-4162

 

[tystaco]

I am in PA and I bought this truck in PA. It's been in PA since day 1.

Amazon is saying this is not compatible with my 1999 Toyota 4runner but I swear it said it was compatible when I purchased it.

I don't know how widespread the CA rigs were, but you'd know pretty quick by if you have a single cat (federal) or double cat (CA).

 

[Mudeprived]

I don't know how widespread the CA rigs were, but you'd know pretty quick by if you have a single cat (federal) or double cat (CA).

Well both of my factory sensors have the same plug. This new upstream has a different connector than the downstream so I am guessing it is the California sensors mislabeled or placed in the wrong box. Amazon is next day-ing another 234-4162 to see if I get the right one now. They are also confused on why their site is stating it does not fit my vehicle yet all the reviews are stating it does. They said it fits IF you click 2wd but does not fit in 4wd. Strange. I confirmed it's the right part on Denso's site so we will see when I get the new part tmw or Friday.

 

[tystaco]

Well both of my factory sensors have the same plug. This new upstream has a different connector than the downstream so I am guessing it is the California sensors mislabeled or placed in the wrong box. Amazon is next day-ing another 234-4162 to see if I get the right one now. They are also confused on why their site is stating it does not fit my vehicle yet all the reviews are stating it does. They said it fits IF you click 2wd but does not fit in 4wd. Strange. I confirmed it's the right part on Denso's site so we will see when I get the new part tmw or Friday.

Now that you mention that, the one I returned was actually the wrong O2 sensor than what was shown...didn't have a flange or gasket. I bet 234-4162 will work if you get the actual part.

 

[TheDurk]

I am in PA and I bought this truck in PA. It's been in PA since day 1.

Amazon is saying this is not compatible with my 1999 Toyota 4runner but I swear it said it was compatible when I purchased it.

https://www.amazon.com/Denso-234-41...=UTF8&qid=1503523198&sr=8-3&keywords=234-4162

That by itself means nothing. My '99 was bought new in NJ and it's a Cali. But if your front and rear factory plugs are the same, that means it's Federal.

The Denso web site shows you what the plug on 234-4162 looks like:

It also confirms it is the correct upstream sensor for a Federal (non-Cali.) '99 4wd Limited (Auto)"

234-4162
Engine: V6 (3.4L)
CC: 3378
1
Note: 4WD; Exc. Calif.; Auto Trans
Label: OE Style
Position: Upstream

Looks to me like you got the correct234-4162 sensor and your factory plug is for a Cali A/F Sensor. Are you sure your upstream and downstream plugs are the same? Because that plug on the right should not fit where an O2 sensor is called for.

Post a pic of your emissions label under your hood and we can confirm whether you have a Cali or not.

 

[Mudeprived]

I am sorry I was wrong and turns out I do have the Cali emissions.

I ordered the 234-9002 but received a sensor with Denso 234-9001 on the part. Is this one ok to run? I looked it up and it says for 4runners 2000+ but not 1999.

 

[TheDurk]

I am sorry I was wrong and turns out I do have the Cali emissions.

I ordered the 234-9002 but received a sensor with Denso 234-9001 on the part. Is this one ok to run? I looked it up and it says for 4runners 2000+ but not 1999.

The only difference among the Air/fuel sensors is wire length. As long as the wire length works, it will be fine. If it's too long, just zip tie it so it won't hit the exhaust pipe. If it's too short, it won't work obviously.

So were you wrong when you said upstream and downstream plugs are the same on your truck? Because that would mean Federal, not Cali. because the air/fuel plugs are different from the O2 plugs.

 

[Johnnie]

no matter how many times I read the postings on O2 sensors it's never 100 percent clear. I want to order a sensor for my 99 3.4 auto. if I read the postings right mine is a cali version (2 cats) I want the rear sensor which screws into the exhaust pipe as opposed to the front which has 2 studs and nuts and a flange. no matter how hard I try to look this up every thing online shows a sensor for 2 studs and a flange. I went thru a toyota parts site and came up with a part number of 89465-49135 even that site shows a picture of the flange type sensor. ?????????????????? my brain hurts!!!!!!!!!!!!!!!I confirmed my vehicle is a California by the sticker under the hood. no matter where I look every site shows a flange type sensor in the aft position , anyone have any ideas

 

[TheDurk]

no matter how many times I read the postings on O2 sensors it's never 100 percent clear. I want to order a sensor for my 99 3.4 auto. if I read the postings right mine is a cali version (2 cats) I want the rear sensor which screws into the exhaust pipe as opposed to the front which has 2 studs and nuts and a flange. no matter how hard I try to look this up every thing online shows a sensor for 2 studs and a flange. I went thru a toyota parts site and came up with a part number of 89465-49135 even that site shows a picture of the flange type sensor. ?????????????????? my brain hurts!!!!!!!!!!!!!!!I confirmed my vehicle is a California by the sticker under the hood. no matter where I look every site shows a flange type sensor in the aft position , anyone have any ideas

The screw-in rear O2 sensor was only MY '01 and '02. Full stop, no doubt. I think someone put an '01-'02 rear cat and sensor in your '99 rig--or possibly the whole exhaust system. Are you absolutely sure it's a '99? Because I have a '99 Cali' I bought new and I can guarantee the rear sensor is a flange and stud setup from the factory.

If it really is a Cali. '99, then the question is was it working fine for a good period of time? Why are you replacing the sensor?

If all has been well, I would go with the rear sensor of an '01-'02, because that is the only screw-in you will find. If you just bought it, and it quickly gave you a code, you may have been screwed by a little Frankenstein mechanics that didn't work--for long.

My guess is, done right, it would work, but it's just a guess.

Give us the whole story and maybe we can figure this out. Feel free to post a pic of your emissions label under the hood.

 

[Johnnie]

wrong O2 sensor?

its been working fine for the last 25K that I have owned it until a few months ago, blowing codes within a mile of resetting it, I replaced front sensor and that solved the code problem except the last four tanks the fuel mileage was 13,16,16,16 MPG after being religiously 20-21 MPG for 25K miles. thought I would replace rear sensor because of the gas mileage and also many people say to replace sensors in pairs. that's when I discovered this conundrum. I think the 01-02 denso screw in sensors are actually reasonably priced 50$ish. I have double checked it is a 1999 model , sticker under the hood says California emmisions and I thought dual cat confirmed this as well. definitely a screw in sensor in the rear position

 

[TheDurk]

its been working fine for the last 25K that I have owned it until a few months ago, blowing codes within a mile of resetting it, I replaced front sensor and that solved the code problem except the last four tanks the fuel mileage was 13,16,16,16 MPG after being religiously 20-21 MPG for 25K miles. thought I would replace rear sensor because of the gas mileage and also many people say to replace sensors in pairs. that's when I discovered this conundrum. I think the 01-02 denso screw in sensors are actually reasonably priced 50$ish. I have double checked it is a 1999 model , sticker under the hood says California emmisions and I thought dual cat confirmed this as well. definitely a screw in sensor in the rear position

You have been Frankensteined. That is not the correct rear cat for your truck. It may even be a universal aftermarket cat.

So now, you don't get any codes, but the mpg is way down? Cuz I got bad news, the rear sensor has no effect on mpg; all it does is set codes. I don't buy the sensors in pair thing, either. The rear ones last longer as they see way less heat. In Cali's like ours, the A/F sensors are more sensitive and go faster than the simpler O2s. I got 30k more out of my factory rear sensor after the front went.

Is there anything else you did at the same time that could explain the mpg change? Because I think you are barking up the wrong tree. What was the code you were getting when you replaced the front A/F sensor?

 

[Johnnie]

I can't think of anything else I did other than looking over everything for loose/broken etc. wires hoses whatever. I did replace the battery about the same time but that shouldnt reset anything with the computer (would it???). I would think with that big of a drop in gas mileage it would be kicking out some type of codes for being too rich??? driving habits have been the same

 

[TheDurk]

I agree it's a head scratcher, but I don't think a new rear O2 will fix it. Have you cleaned MAF and throttle body?