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The shade tree mechanic

Discussion in 'The RoundTable' started by shane0911, Apr 4, 2014.

  1. shane0911

    shane0911 Veteran Member

    Okay, so my wife has an 08 expidition (I have always hated ford and now I hate em even more) and I'm getting a P0420 which is the emission system is operating below threshold.

    My question is have any of you had a similar problem and what did you do?

    I'm probably going to change both the up and down stream 02 sensors first, about $50 each and hope like hell that fixes the problem. If it doesn't that more than likely means it is the cat and I don't even want to know what that will cost.

    I wish someone would just steal that MF'r
  2. KyleK

    KyleK Who, me?

    Before you buy new O2 Sensors, try cleaning the rear one. BTW, it would typically be the rear one that is bad. If cleaning it doesn't fix the problem, pick up an O2 extender from AutoZone for $5 and install that between the sensor and the pipe. That should clear the code.

    How is the performance of the car? Does it otherwise run normally?
  3. mobius481

    mobius481 Registered Member

    I had an 08 expedition and loved it. I take that back. I bought it in 08 but it was an 05. Just traded it in last year.
  4. shane0911

    shane0911 Veteran Member

    Man it seems to run okay. I just got it back from the shop. I had a heater hose that was leaking coolant onto the coils and caused 2 of them to go bad so those got replaced. I'm hoping that the fact that these 2 coils are now working properly has something to do with the code. I'm going to have the code cleared and see if it just doesn't come back.
  5. KyleK

    KyleK Who, me?

    That has everything to do with the code. You had unburnt fuel going downstream. Hopefully it didn't coat the Catalytic Converter too badly. Cleaning your rear sensor should suffice.
  6. KyleK

    KyleK Who, me?

    Is 0420 the only code? If so, your problem is the rear sensor or the cat itself. The O2 extender will clear the code, but if you have to have a smog check and the cat has failed, then you won't pass.
  7. shane0911

    shane0911 Veteran Member

    No smog check in Oklahoma bro
  8. KyleK

    KyleK Who, me?

    Then you are good. Get the extender and you should be fine. 5 bucks
  9. shane0911

    shane0911 Veteran Member

    Im going to clear the code and see if it comes back. If it's the cat though how will this extender help?
  10. KyleK

    KyleK Who, me?

    The cat will get fouled and keep setting the code. The extender keeps the code from setting by taking the sensor out of the exhaust stream.

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