i have an 01 blazer with 185k miles on it and i have been fighting poor gas mileage. It has been recommended to me to change the oxygen sensors before the cat as they , over time, start to degrade. Does anyone know if this truck is sensitive to which sensors it uses. I have found some replacments ones for about half the price of bosch or denso. Thanks

 

Personal experience with 02's on a 96 blazer w/186k. My vehicle has 4 sensors. I not exactly sure why Bosch is rated so highly, but i will NEVER use Bosh 02's again...NEVER! Had nothing but problems.

I have used OEM, Borg Warner, Standard Motor products with no problems. Hope this helps. Also, check out ebay for those 02's sensor.

 

Your 2001 will have 3 sensors. Only the upstream (those between the exhaust manifold and the "y" in the y-pipe) have anything to do with fuel delivery. Beyond the y-pipe, emissions monitoring only.

And AC Delco sensors are all that I recommend. I have heard good things about the NGK O2 sensors, but have never used them. I have had too many problems with other makes including Borg Warner & Standard Motor.

Also, get the ones that plug right in. DO NOT get a universal fit sensor.

As far as your fuel mileage issues go, when was the last time you performed a complete tune up. If you have done a tune up consisting of plugs, wires, cap, & rotor, what brand of plugs did you use. The AC Delco double platinum plugs should be used as others have been known to cause decreased performance/efficiency.

 

First i just want to say thanks very much for the help and ill just order the OEM sensors. I did see NGK ones at advance for 25 dollars but ill just order OEM. As far as tune up, i didnt put that in here becuase of double posting. I have a thread called "01 blazer bad gas mileage" that is very recent. Short answer is very recently did i do a complete tune up with OEM delco platnum plugs. These sensors are my last effort to increase my mpg before i say heck with it leave it alone. I have done everything i can think of except for clean EGR and these sensors.

Thanks very much.

 

Also what about DENSO, i can get those locally but know nothing about them.

 

Denso aren't supposed to be that bad in GM vehicles and in the testing that I did, they showed similar activity to the AC Delco's, but just not quite there. If the prices were the same, I would say AC Delco.

 

well the densos are about 20 dollars per sensor cheaper but im not going to risk it. I ordered two AFS105 AC delco sensors from rock auto 140 dollars shipped. Do i need the special socket for this vehicle. I just used a wrench for my old truck when i replaced it.

 

A wrench should be all that you need. There is pretty good access.

 

If they are not rusted in a wrench will work. If they do not want to come out most auto stores have a loaner 02 sensor socket kit. Make sure the new ones have anit sieze on them but don't get any on the tip of the sensor.