O2 sensor part number help

Discussion in 'General Chevy & GM Tech Questions' started by Pikey, Nov 30, 2012.

  1. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    My 05 yukon xl has had a decrease in fuel economy over the last couple weeks (from 19-21mpg on the freeway to just over 17mpg). I have not changed anything, use the same gas, same tire inflation, MAF and Throttle body are clean, spark plugs new, air filter new, fuel filter not changeable. So, using my obdII monitor I noticed that my o2 sensor reading are all over the place. I am sure that this is some what normal, but I mean with the cruise set at 68mph the readings hop all over from 38 millivolts to over 700. I may have the correct O2 sensors "in stock" in my basement or my fathers basement. This is where the problem is: There are no markings on the sensors that are in it now. I crawled under the truck and the pre and post cat sensors look exactly the same. Same plug on the end. Same color wires. Same wire placement in the plug. So, here is the question, "what is the difference between the two"? one heated, one not? does it matter if I use the same sensor for all 4 locations? :neutral: Being that I may have them sitting here and I will not have to pay $60 each, I will be more likely to swap them out. I found the GM part numbers 213-1702 (12587785) Pre-cat and 213-1699(12576131) Post cat online. But, The sensors I have are not in a bag with the part number on it. I know that someone here is magic with these situations. @99'HEARTBEAT has saved my rear multiple times already with this stuff. :whistle:
  2. Jamm3r

    Jamm3r Member 2 Years 100 Posts

    I have not replaced O2 sensors on my 2004 yet but on most other cars and trucks I've worked on there is very little difference between upstream and downstream sensors. Sometimes the connectors differ, sometimes the length of the pigtail differs. There are times I've soldered an upstream connector on a downstream sensor because that's what I had in my shop. I would suggest using whatever you have if it will fit and monitor the results.
  3. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Well, I have a box with over 100 new O2 sensors in it. None of them matched my part numbers. I had many with the same connector as mine, but none with the same number. I am concerned because they are heated and I am not sure that all of them with that connector are heated.

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