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  1. 08 H6 Outback, misfiring and multiple codes including P0420, P0026

    Problems & Maintenance
    I have had the P0420 code intermittently popping up over the past year or two. Earlier this year I noticed my gas mileage starting to get worse, and I am not sitting at 12/20 while it used to be at 18/27. I have replaced both upstream O2 sensors, and a read one that was showing weird voltages...
  2. Attempting to Use Overformatted Data to Fix P0420

    Gen 3: 2005-2009
    Hi friends, I recently had my first run-in with the infamous P0420 code (Catalyst System Efficiency Below Threshold) on my 2006 Outback 2.5 Limited. The CEL has been on with the P0420 code for probably about a month now. At first, it was intermittent and would sometimes go off on its own (I...
  3. 05 Legacy Wagon, 2.5gt, Lemon??

    Gen 3: 2005-2009
    Hello, I am new to this style of forums, but I am determined that others are the best way to resolve my problems with my new Subaru. Here is the backstory: Bought a 2005 Subaru legacy Limited 2.5gt wagon Tuesday, 11/12/19, I test drove it, felt smooth, fast, very clean car no lights or issues...
  4. O2 sensors California model

    Gen 3: 2005-2009
    I’m sure I’m asking a question that is already out there but I’m not finding it. I have an 05 base model California exhaust. I have a P0420 code that I’m going to replace the O2 sensors first before I replace the catalytic coverts to see if that corrects the CEL. Under the car I have the 2 up...
  5. 2006 Outback - Replacement Cat, will it pass CA emissions

    Problems & Maintenance
    Hi all, first time poster, thanks in advance for your collective wisdom. 2006 2.5L 5speed Outback Test group: 6FJXX02.5NVD Been driving with the MIL on for the last 3 months, ignoring the P0420 I've been getting. As of yesterday, can barely make it up hills on the freeway, so I think the time...