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Thread: O2 Sensors

  1. #1

    Default O2 Sensors

    Okay, Folks,

    I had my "Check engine" SYMBOL (not the words) light up on me the other day. My mechanic friend threw his scanner at my Truck, and it returned a "O2 Sensor Heater" Code. Bottom Line is, I need to replace one of the four O2 sensors on my truck.

    WHY is there so much variance in price, for O2 sensors? I am talking anywhere from $25/sensor, to $125/ sensor. Is there REALLY that much difference in the quality or operation of the sensor? Isn't an O2 sensor just a piezoelectric thermalcouple type of device??

    Secondly, why does an O2 Sensor need to be heated? It's funny, that my Truck kicked this code off, during one of the coldest periods around here in some time. We did see and honest to goodness 9 degrees F one morning. MY O2 code popped about three days later.

    Thanks, and look forward to comments!

  2. #2

    Cool o2 sensor

    What type of truck and year?

  3. #3


    You didn't say what kind of truck you have but here's a few tips. When you get an O2 heater code it can be a bad connection somewhere in the circuit. O2 sensors need to heat up as quick as possible so the PCM can go into closed loop. It's an emission thing as a slow warm up wastes gas and pollutes. Cheap generic O2 sensors usually don't last, are very hard to install because the wires are not the same as OE and you have to match one color wire to a different color wire which is a PITA. Before you buy a new sensor why not tell us what kind of truck you have and the actual code description?

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
    Tinted Windows

    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

  4. #4


    Sorry guys, haven't had time to check back here!

    Forgot SOME specifics, huh?

    Well, first of all, it's Red!


    My Truck is an 04, Z71, with the 5.3 L V-8. The exhaust is only modified, from the muffler rearward. I installed a Flowmaster muffler some 5 years ago. I do have a cold air induction system, with K&N filter, again having been on the Truck since basically new.

    I am not 100% sure, what the specific code popped on my friends scanner. Normally, everything he needs to see, is displayed on the scanner. However, this time, he mumbled some numbers, as he headed toward his computer. After that, he let me know what he had learned.

    More info. We reset the Check Engine symbol on Friday afternoon. The following day, I logged better than 200 miles on my Truck. The code never displayed. Then, on Monday morning, the code came back. It should be mentioned that on Saturday, the temperature never dropped below 50 degrees, F. On Monday morning, the temperature was around 30 degrees, F.

    Anyway, just trying to be a little educated on these sensors. My mechanic friend, who deals with sort of thing often, is NOT recommending the cheapie stuff, but doesn't suggest buying the $200 stuff either. Also, some part numbers for the before/after O2 sensor are different (different parts?), while other manufacturers show that one part will work before OR after the Cat.


    Oh, and Thanks guys for your input!

  5. #5


    I think the reason for the same part numbers is they give you a generic sensor which splices in to your old connector. The good ones are specific to the location which in most cases has a different connector plug configuration front to rear.

  6. #6


    Another update:

    Check Engine Symbol light, went off today. Air temp = mid 60's, F. We aren't supposed to get out of the 30's tomorrow. I bet the light comes back on!

    Don't you just love Texas Weather??


    I was pretty confident, that the part was interchangeable, just a wiring connection that was different. It was good to get some sort of confirmation on that way of thinking. I am tempted to crawl under there, and pull a before and after cat sensor out, and compare the two.

    I'll keep you guys posted.

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