cant find oxygen sensor

Discussion in 'Trucks and Trailers' started by Indy Kyle, Jul 6, 2008.

  1. Indy Kyle

    Indy Kyle LawnSite Member
    Messages: 157

    99 f250 v10
    I have a service engine light that came up as -running too lean, bank 2- guy at parts store sold me an oxygen sensor said it was the downstream sensor. Said it was after the cat. For the life of me I can't find a sensor after the cat. Theres nothing there. I see 2 coming out of the exhaust manifold under the block. (1 on each side) but that's all I see. My truck sits up plenty high so I have a clear view all around and it just isn't there.
  2. maintenanceguy

    maintenanceguy LawnSite Member
    from NJ
    Messages: 156

    A scanner (not code reader) will let you look at the output from all the engines sensors while the engine's running.

    You can scroll through the list of sensors and you'll see 4 O2 sensors listed: 11,12, 21, and 22. That's for bank 1 sensor 1, bank 1 sensor 2, bank 2 sensor 1, and bank 2 sensor 2.

    There will be data streaming from the sensors you have, none for the sensors you don't.

    You might not have a sensor after the converter.
  3. Keith

    Keith LawnSite Gold Member
    Messages: 3,979

    I'm sure your 99 does not have a sensor aft cat. And if it is, in fact, a bad o2 it will be an upstream one giving you a lean code. It could very well be something else causing the lean condition, but if the o2's are original, it's a good place to start.

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