Hey everyone. I barely passed my last smog check and my MPG's have been in the low 14's so I figured the truck could use some new O2 sensors. I have a 1999 V6 4X4 automatic Cali emissions 4runner. I checked URD and it said I needed a 234-9002 sensor in the front and 234-4153 in the rear. I ordered them from amazon and when I installed them, the rear one went in fine but the plug on the front wouldn't fit and the sensor had way fewer holes in it. I shaved down part of the plug to get it to fit but when I ran the truck it came up with po135 trouble code (O2 sensor heater circuit). I'm guessing the issue was that it was the wrong part, but all the packaging it came with said 234-9002. I swapped it back out with the old one and cleared the trouble code and it hasn't come back. My question is, how likely is it that Denso just packaged the wrong part? and can someone confirm just for the sake of my sanity that my truck does indeed need a 234-9002 in the front?
O2 sensor issue
- Thread starter yotatake2
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jeremyc74
Banned
that's the sensor I got and it looks like that, but the plug on the old one is different. Which makes me think I might have the wrong part number even though every source says I need the 9002. I'm going to call the dealer tomorrow and have them check with my VIN to see what part I need. What's weird is I checked the reviews on Amazon for the 9002 and out of over 100 reviews, not a single one was on a 1999 4runner. They were all mostly 2001 and 2002.
jeremyc74
Banned
Hmmm....interesting. Maybe the '99 CA models were different.
TheDurk
Elite Member
Are you sure you are a Cali.? If the plug on a 234-9002 doesn't fit, that pretty much tells me you aren't Cali. I am a '99 Cali. and the 234-9003 A/F works perfectly because I have a manual; 234-9002 would be right if I had an auto. All the flange o2's, all the screw-in O2's and all the A/F's have the same plug within their respective classes. Only difference is wire length.
Exactly why do you think you have a Cali? Some people mistake the resonator for a second cat.
What does your emission label say in the top left corner--the line right under "Engine Family"?
A/F S, TWC(2), HO2S = Cali.
HO2S(2), TWC = Federal.
Ignore other letters, these are what count. Don't rely on the rest of the label--the verbiage can be very misleading.
If you want further proof, see if the rear sensor plug would have fit in the front connector before you butchered it (or hopefully, the connector is intact and you did your surgery only on the sensor side.) If so, you are not a Cali. and you need an O2 sensor in front.
Exactly why do you think you have a Cali? Some people mistake the resonator for a second cat.
What does your emission label say in the top left corner--the line right under "Engine Family"?
A/F S, TWC(2), HO2S = Cali.
HO2S(2), TWC = Federal.
Ignore other letters, these are what count. Don't rely on the rest of the label--the verbiage can be very misleading.
If you want further proof, see if the rear sensor plug would have fit in the front connector before you butchered it (or hopefully, the connector is intact and you did your surgery only on the sensor side.) If so, you are not a Cali. and you need an O2 sensor in front.
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Rear sensor has the same plug pattern as the front. I guess I just wrongly assumed it's a cali model since I live in cali and passed California smog. I'll have to double check the numbers to make sure. I added the rear sensor that was recommended for the cali models and the mpgs dropped even more and i've lost alot of power so maybe that's what's doing it.
Holy shit, I'm a moron. My truck isn't California emissions. I just assumed it was since I live in Cali and it passed the Cali smog. Goes to show you just how little I know about emissions. I should have realized it when I looked at my buddy's 3.4 and the evap system looked totally different. So I actually just need 2 of the 234-4162