oxygen sensors

[JoshBarber]

Originally Posted by BlazerLT

Should be part of a preventative maintenance.

How many miles and what year is yours?

98 4.3L LT 4x4
104k miles.

I was told there were 4. But they're not cheap. I think like $200 for all four. Do you reccommend I wait until I have a code, or symptoms? Or replace them now. Keep in mind I have little money. Should I stick with just the fronts if so?

[BlazerLT]

Originally Posted by JoshBarber

98 4.3L LT 4x4
104k miles.

I was told there were 4. But they're not cheap. I think like $200 for all four. Do you reccommend I wait until I have a code, or symptoms? Or replace them now. Keep in mind I have little money. Should I stick with just the fronts if so?

You are getting in the range where you should start thinking about replacing at least the three before the cat. The one after the cat is not so important seeing it only monitors the cat for efficiency.

[wolfox]

My '95 has only one pre-cat sensor as well. Seems that there was a change over to full OBD-II systems in the middle of the production run and we start seeing pre & post calayst sensors appearing...then the massive 4 sensor configuration in '96 onward.

[rlith]

Originally Posted by wolfox

My '95 has only one pre-cat sensor as well. Seems that there was a change over to full OBD-II systems in the middle of the production run and we start seeing pre & post calayst sensors appearing...then the massive 4 sensor configuration in '96 onward.

Some 95's (like mine) have 3, so have 2 (any with 3 or 2 have the ECM under the hood for 1st revision of ODBII) 1 sensor will be ODBI.5. Also same with 96 to current. Some have 3 some have 4, no pattern I can discern on why some 3 or 4...

[TonyMazz]

I have 158000 on mine and haven't changed them. I continue to get 18-22 mpg. No codes or issues....I suspect that I will begin to see either a decline in Mpg or SES eventually.

Dealer techs tell me..."if it aint broke don't fix it".....worst will be sucky gas mileage, and SES.

The risk vs cost says to me...says wait.....it's not a castrophe if you through a code....

OK I'm ducking now fire away haha !!!

[BlazerLT]

Originally Posted by rlith

Some 95's (like mine) have 3, so have 2 (any with 3 or 2 have the ECM under the hood for 1st revision of ODBII) 1 sensor will be ODBI.5. Also same with 96 to current. Some have 3 some have 4, no pattern I can discern on why some 3 or 4...

3? 1 or 2 only.

[rlith]

I can most definatly say I have 3, and 3 other 95's that I have worked on have 3... Hell, I didn't just spend 150 bux on 02 sensors last weekend for nothing...

[Fireplug]

The 1995 Blazer is a half breed. Its working on a basic obd2 system. Had to have special adapters for the GM Tech Tool to work on it. It was a big pain in the butt

[rlith]

Originally Posted by Fireplug

The 1995 Blazer is a half breed. Its working on a basic obd2 system. Had to have special adapters for the GM Tech Tool to work on it. It was a big pain in the butt

Actually the flash I recently got at the dealer made mine totally ODBII compliant instead of first revision...(See my other thread on the subject )

[BlazerLT]

Originally Posted by rlith

I can most definatly say I have 3, and 3 other 95's that I have worked on have 3... Hell, I didn't just spend 150 bux on 02 sensors last weekend for nothing...

Where are they located?

[rlith]

On mine, one on the down pipe just after the flange, one just before the cat, one just after, none on the driverside down...

[BlazerLT]

Ah, I have one before and one after the cat only.

Guess I got lucky.

Simpler, the better.

[jon@af]

Back open for business (after a bit of cleaning). Defient, if you post anything else in this thread bitch towards BlazerLT, I will delete the post and ban you. The issue is over and done with. End of discussion.

[westsider]

I have a 1996 Blazer and I would also like to change the o2 sensors. but I just wanted to know if you really need that special socket to get them off. Which kind of o2 sensors did you guys use? Is there any difference? I havent checked how many o2 sensors I have but should I only change the ones before the converter. Thanks for any help

[rlith]

Originally Posted by westsider

I have a 1996 Blazer and I would also like to change the o2 sensors. but I just wanted to know if you really need that special socket to get them off. Which kind of o2 sensors did you guys use? Is there any difference? I havent checked how many o2 sensors I have but should I only change the ones before the converter. Thanks for any help

Simply use a 7/8th box wrench (spray with some pb blaster an hour or more before taking them off) If you can avoid burning yourself on the pipe, run the car to operating temp so it makes it easier (obviously turn the car off when you go under it).... As far as sensors go, Plain bosch works just fine (bosch makes the OEM sensors as well)... You can get them at any autoparts stores.