oxygen sensors

gmbwrenchn · #1 10-17-2004, 11:25 AM

Blazer 108k miles. Should oxy sensors be changed even if there are NO problems with the vehicle just as a prevenative maintance program? How many are there on a Blazer? Thanks.

86TATpi · #2 10-17-2004, 03:09 PM

Over time the element in the front oxygen sensor becomes less sensitive to oxygen in the exhaust, reducing how quickly it will adjust to change in exhaust. It's over all up to you, I would change it. The rear oxygen sensor monitors the effectiveness of the catylitic converter by comparing the front sensor readings to it's own. I don't change the rear one unless the SES light turns on.

gmbwrenchn · #3 10-17-2004, 04:40 PM

Thanks. So I take it there are two. What does SES
stand for?

BlazerLT · #4 10-17-2004, 07:03 PM

What year do you have and yes, you should change them.

I changed mine and got a 3MPG increase.

Mikado14 · #5 10-17-2004, 07:37 PM

Hold on, you don't know what year Blazer. '94 and older will have only one and it is pre-cat. I worked on a '96 two weeks ago and it had 4. One on each downpipe from the manifolds, a pre-cat and a post-cat.

BlazerLT · #6 10-17-2004, 07:49 PM

My 95 has a pre and post cat sensor.

Mikado14 · #7 10-17-2004, 07:51 PM

And there you go, there's 3 variations on Blazer's that GM has done. The '96 was a Jimmy but I fail to see if that would be a difference.

gmbwrenchn · #8 10-17-2004, 08:32 PM

97'

gmbwrenchn · #9 10-23-2004, 06:11 PM

looks like there are 2 oxy sensors. 1 before the catalitic converter and 1 after. Is that it?

BlazerLT · #10 10-23-2004, 08:23 PM

There will be one also in the exhaust pipe coming down from each manifold too.

gmbwrenchn · #11 10-23-2004, 09:45 PM

Thanks, for the info.

Alexxn 00 Si · #12 10-24-2004, 08:54 AM

Do you need to use GM O2 sensors or are aftermarket (like Bosch) OK ?

BlazerLT · #13 10-24-2004, 09:21 AM

Bosch are completely fine.

Bosch actually designed GM's O2 system.

JoshBarber · #14 02-13-2005, 09:53 PM

Quote:

Originally Posted by BlazerLT

What year do you have and yes, you should change them.

I changed mine and got a 3MPG increase.

did you have any symptoms before deciding to replace your sensors? Or did you just do it as preventative maintenance? I assume you just changed the front two? there ARE 4 right?

BlazerLT · #15 02-13-2005, 09:57 PM

Should be part of a preventative maintenance.

How many miles and what year is yours?

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