I got a "check engine" light the other night....plugged the laptop up to the obdII and the codes were:

-O2 Sensor Circuit Error
-O2 Sensor Slow-Response

I cleared the codes and after driving for about 10min got the check light again....Even with the check light on, it still drives fine...I'm ordering a new front O2 sensor ($88) My question is about the rear O2 sensor...this would not need to be replaced right? I was under the impression that the rear O2 was pretty much useless and it would be a waste of money to replace it. (same with my Supra's rear O2)

Also, its about time to replace my plugs...right now I have the stock plugs and I was reading about the 1 step colder irridium plugs (~$90 for 6 made by ND/TRD)...is this the recommended plug for SC applications? or would stock do me just fine?? Does NGK make a 1-step colder plug (for only a few $'s each)??

If my O2 has been on its way out...I'm sure with a new one, I'll see a gas milage improvement and possibly an improvement in performance

Thanks in advance,

 

I can't answer your O2 question.

But I have the NGK BPR7ET (Gadget recommended) which is a two step colder plug. Do you have any pinging problems?

 

How do you know the codes you pulled were not from the rear O2 sensor?

 

I very rarely have pinging problems....only occasionally holding a speed up a hill, the usual ping situation. But even then, it doesnt ping much.

Any idea how much of a difference 1 step colder to 2 step colder would make? Are there any drawbacks to the 2 step colder plugs?

 

If I remember the code description correctly, it specified "Main Oxygen Sensor"

 

Ok, gotcha. How much is the rear? Are you going OEM?

 

Both O2 Sensors are $88 ala Curt Aigner...Is there another option to stock? *other than wideband*

 

I just got the check engine light the other day. When I hooked up the OBDII it told me PO133 O2 sensor circuit slow response (bank 1 sensor 1.

I also have 96 v6 and I am going with a denso O2 sensor which is the same as the OEM. Your right about the rear O2 being useless. It only operates 10% of the time.

Later model years I beleive 99 and up would need to replace the air/fuel ratio at about $300. Theres two in the front and two in the back for those model years.

 

What do you mean "replace the air/fuel ratio" ?

 

I think he is referring to the air/fuel ratio sensor (it's called something like that) that some some 4Runners have instead of a front O2 sensor. I believe they came on CA spec 4Runners for emissions reasons. There was just a discussion about a week or so ago about this - somebody ordered a regular O2 sensor when they actually needed the air/fuel ratio sensor.

Sorry if that isn't what exactly they are called, but I think it's close.

 

air/fule ratio sensor is what I meant. they are pretty expensive.

 

nice...you have a link for the denso O2 that fits the 4Runner?? cheaper than OEM? thanks

 

Bank 1, Sensor 1 is the front sensor......I have never seen anyone get a sensor 2 error but I am sure it is possible and of course that would be the rear sensor.

The rear sensor rarely goes out because it gets much less exposure due to its placement downstream of the catalytic converter. It is only a corrector or modifier to the ECU where the front sensor is the actual workhorse of the EFI feedback system. This is also why it is replaced far more often that the rear.

As mentioned already, do make sure you get the correct part for your VIN# truck. You want to replace with the same sensor be it the O2 or Air/Fuel ratio type.

 

Toyota part number 89465-3985
Denso Part number 234-4162


See what price you get on a Denso O2 sensor. I might be able to get you a better deal.

 

I just went through the same fiasco. Got a bank1 sensor 1 code, and the dealer gave me the wrong part. Toyota calls it the 'Air/Fuel Ratio Sensor', and wants $300+ for it. I got one at a j-yard off a 2001 for $45.
They shipped me a rear O2 sensor in the bag on accident, but I don't need it. If anyone wants to replace theirs, I don't need it, $20 shipped.