OBD II hell

[midwestern]

help...

ok i have a 96 fzj 80 with 109,xxx on the clock. my obd2 scanner showed both o2 sensors needed replaced and with the mileage i didn't' hesitate. i went with the bosch sensors oem type (no splicing needed) from autozone not just for the price, but also they had a 1 yr warranty.replaced them and my truck definitly felt smoother than before. the next day i start my truck up and boom. another cel code. it read o2 sensor 1 heating element bad. sensor 1 bank 1. irate i thought the sensor was bad so i went back to autozone got a new one. and today i got the same damn code. i have read old threads on this subject now (after all of this mess) and my question is it truly the sensor or something else. both times the code was thrown it was a cold start and my rpms reved quite high, the revs went down and the code was thrown. is this all caused by these bosch sensors? i was really under the impression that all o2 sensors are very similiar and i have never had this problem with any other vehicles i have worked on. i know some of you are running these sensors. have you had the same problems? the truck seems to run smooth still, but i really really really hate cel's, espically after spending the $$$$ and time. thanks all, this site is great!

Ryan

 

[BGarcia88FJ62]

I'm not really an 80 guy but on my FJ62 you need to clear the codes. Typically I just disconnect the baterry for about 15 min. that usaully clears my ECU. Not sure if that will do it for you but something to think about.
.

 

[FrankTorres]

help...

i went with the bosch sensors

Ryan

That might be your problem...Denso or NTK from your dealer would be better.

 

[CJF]

Check the wiring.

I'm pretty sure some folks have found frayed O2 sensor wiring under the chassis somewhere.

But yeah, OEM would have been better.

Curtis

 

[nicholas]

I had the same problem. Before I found MUD, I replaced the front O2 sensor with a bosch.:whoops: The CEL stayed of for a very short while, then it came back on. I didn't bother with the warranty since I knew it was $60 down the drain anyway since I needed to buy some Denso's.

I bought 2 new OEM Denso sensors from CDan and my CEL has not been on since I put them in. The back one didn't really need replacing, but I did it anyway while I was at it since it had 139K on it.

It might be worth getting some new OEM ones from Dan.

 

[KLF]

I'm not really an 80 guy but on my FJ62 you need to clear the codes. Typically I just disconnect the baterry for about 15 min. that usaully clears my ECU.

Disconnecting the battery won't clear the code for OBD-II, you have to clear it with the reader.

 

[Darwood]

Disconnecting the battery won't clear the code for OBD-II, you have to clear it with the reader.

Not true. Disconnecting the battery for 15 minutes will clear the codes. I think pulling the EFI fuse for about 15 minutes will do the same thing.

 

[MikePL]

Pulling the EFI fuse for 3 seconds is absolutely enough to clear the codes. Ale least on my truck.

You get an error because the Bosch sensors have a heating element which has a different resistance. All your sensors are good, they simply are not matched for that vehicle. Yes, I know that all shop/website systems point to those Bosch sensors but they are simply wrong. The sensors itself would be fine for the 1996 FZJ80 but the heater is not for it and the ECU throws a code.

You will need to look for NGK or Denso O2 sensors and I hope that someone will chime in and give the right resistance you need. The resistance of O2 sensors changed in the 80 series for the 96-97 models (with the introduction of OBDII)

 

[midwestern]

thanks guys! in response i cleared the code twice with the reader and the battery. i think these are going back to the store since i have the warranty. the code has come back each time. i don't know what insanity would have errupted if i hadn't heard from you guys! i checked all the wires ...for hours. thanks putting the stock on. should have stuck with denso in the first place. oh just for my info. are the bosch sensors actually performing the job correctly and just throwing the code , or are they actually consistantly sending the ecu incorrect info?

 

[midwestern]

are there only one model denso sensor for this year and truck? i just don't want to get the wrong ones again.

 

[nicholas]

thanks guys! in response i cleared the code twice with the reader and the battery. i think these are going back to the store since i have the warranty. the code has come back each time. i don't know what insanity would have errupted if i hadn't heard from you guys! i checked all the wires ...for hours. thanks putting the stock on. should have stuck with denso in the first place. oh just for my info. are the bosch sensors actually performing the job correctly and just throwing the code , or are they actually consistantly sending the ecu incorrect info?

In my situation, I believe they were sending the wrong information because I could tell the engine was running rich and the exhaust smelt horrible. I even had a shade of black carbon that would collect on the rear hatch.

are there only one model denso sensor for this year and truck? i just don't want to get the wrong ones again.

If you get them from CDan you will be guaranteed to get the right ones. I think they were about double the cost of the bosch, but obviously worth it. Definitely cheaper than the $400 the stealership in Spoakne wanted for a pair of them.

 

[smokethedog]

What code are you getting and how many miles do you have?

Check the exhaust connections/gaskets between the cats and behind the 2nd cat and see if you have an exhaust leak. I think I had that issue on my rig several years ago.