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  • PO 420 & 430 codes

    Ok, I'm pulling my hair out or what little is left. We recently bought a used 08 3.0 AWD Escape from a local lot. It's a very clean, well taken car of car, 1 owner, woman with a clean car fax. The back story, when my wife took it out for a test drive before we bought it, the car died. The dealship with a very good reputation was very apologetic especially since they had driven the car about 100 miles from the auction lot. The idle air bypass went bad which seems to be a somewhat common issue on these cars what I read. They fixed it, we bought it. The car was running great then the check engine light went on. The codes were both banks lean, O2. The dealer told us to bring it in right away. The car was running fine otherwise. They didn't know exactly what caused it but thought maybe something from the bad idle air bypass valve. They cleared it and the car ran fine. A couple days later it started to idle rough and stall. Dealer said to bring it right back. They replaced the MAF sensor and fuel pump. Get the car back, it's idling a bit high, around 1200 in neutral and about 1000 in drive. Again the check engine light comes on, both banks rich. I check the MAF, it's a AZ Duralast. Checking around it seems they have a 50/50 chance being bad right out of the box. I went to the junkyard and picked up a used OEM Ford MAF for $30. That fixed the problem, cleared the two O2 codes for being rich. Car has been running great for about a week and a half. Wife calls me, the check engine light on but the car is running fine. She takes it to the local AZ where someone we know works and checks the codes. 3 of them. One was I think a 422 for a evap leak and the other two, the 420 & 430 which are cat inefficiencies in both banks.

    I find it it odd that both cats going bad at the same time. Could it have something to do with the past issues even if I had cleaned out the codes? What else can I look at? We bought the car without a warranty but even so the dealer has been good about it. I only fixed it because it's a pain to keep going back and leaving the car for a couple days. I don't mind fixing minor stuff, it is a used car. Any help is appreciated. It's been a week with the cars. On another car in the household fleet the rear brakes stopped working. The pistons and calipers move freely, I replaced the MC because the pedal would go to the floor. No leaks anywhere, both bowls full. New MC didn't fix it. Another car, O2 Escape, the PS pump went bad. Had someone replace that because I didn't have the time, now the new pump has an issue. Sheesh, if I didn't have bad luck with cars I'd have no luck at all.
    Tom
    Overdrive is overrated



  • #2
    when you fix a leak, the cat burns it later, it makes something of it long term.... such as coolant.

    given the errors on the air side repaired.. did the car have a pollutant mishap? maybe some water?

    my own truck got an old y-pipe on a very nice engine..created quite a mystery.
    po420 was a cat that it gutted by itself. It had been poisoned by coolant from a previous motor.

    high flow on a gm, the code still goes out.. the ecm respects it. as long as it not cali.

    anyway.. you really might need some cats.
    Last edited by Barry Donovan; December 20, 2017, 12:05 PM.
    Previously boxer3main
    the death rate and fairy tales cannot kill the nature left behind.

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    • #3
      get under the car with a laser, temperature sensor the check the inlet and outlet temps of the cat. It should be at least 100 degrees hotter at the exit. On my Hummer, I'm pretty sure the only issue was there's a wiring fault in the O2 sensor wiring.... that said, I replaced both cats (along with eliminating the unmonitored secondary cats) and got a nice hp increase
      Doing it all wrong since 1966

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