If you don't need it right away, it's $20 cheaper from Rock Auto.

 

So I need the Downstream one , is that correct? Sorry I keep asking all these questions, I just don't want to purchase the wrong part .

 

I really don't NEED it right now, I was just going to pick it up and get it done since it's on my list . I just figured after filling my tank, I should replace the 02 sensor and see what improvements I'd get out of the replacement
?

 

Bank 2 sensor 1 would be considered upstream, since it is upstream from the catalytic converter. Either way, the O2 sensor you linked to would fit both the upstream and downstream O2 sensor locations, so yes it is the correct part. Did you follow the diagnostic chart to see if the sensor is indeed what is causing your P0155?

Edit: Or you should be able to switch the sensor in question with the sensor from Bank 1 sensor 1 and see if the DTC follows it. P0135 would set I think. Someone correct me if I'm wrong about this.

 

So Denso is the OEM O2 sensor? I thought that the OEM was a AC Delco O2? I am hearing that the AC Delco and Delphi brands are very similar if not the same in quality and I find that Delphi is often a little cheaper in price.

 

I was under the same assumption myself in regards to the 02 sensor being one brand or another but that works for me , I'll save a little extra $$ by replacing it with a factory original part .

 

Denso is what came with the engine originally. If you go to a GM dealer and ask for an O2 sensor, you'll likely get an AC Delco, which may or may not be the same as a Delphi. It just depends what vendor it came from. They are both built to the same specifications, and may or may not have come off the same assembly line. My experience is that the response time is faster with Denso sensors, they're cheaper, but they don't last as long as AC Delco & Delphi.

 

I got into the Blazer today finally, I looked over the balljoints, and there is little to no place in them, however the idler arm on the passenger side was bad so I replaced that and the steering seems a lot better almost night and day to be completely honest. With this being said, I will be replacing the ball joints I'm just going to hold off on it now that I can see that they aren't as bad as I was told initially . I also had an a friend of mine whom used to work on the vehicles for my Army unit look at it , and he concurred the same findings so that's a huge weight lifted off my shoulders.

Now off to Advanced to purchase a new 02 sensor so I can at least replace that and get taht off the list , and prep for my trip back to Chicago for the upcoming weekend, hopfully I'll see 20's like I did initally when I drove down to Greenbay when I first got the Blazer and seen 21mpg on the highway .

After all that , I'll be doing a full tune up and just drive it for the time being , I've noticed though that i'm consistently getting 17-18mpg on my commute to and from work, driving 65-73 on average ( highway / country road ) I think after the tune up and a bit of a driving adjustment that will improve my mpg as well .

Chi_Town

 

I am glad you checked the suspension yourself and found the worn Idler arm. that is one of the weak parts on a lot of GM's RWD and 4WD cars and trucks. The good news is it is a lot easier, and cheaper, to replace than the ball joints. Let me mention that I have often read that the 'lower ball joints' wear out much quicker than the upper ball joints. Please let me know if this it not the case. Also if you should replace in pairs/upper and lower. For example you don't replace brake pads on one side, you replace the brake pads on both sides of an axle. I don't think that is the case with ball joints. IOW you can just replace the lowers on both sides.