Just Bought '06 Forester X, Check engine light on with code P0420 and P0457.

FrustratingForesterXFrustratingForesterX Member Posts: 1
edited October 2022 in Subaru
I'm new to the forum and trying to find answers to a few issues with a 2006 Subaru Forester X I bought about a month ago. First of all, it is automatic. When I start the car it idles around 600 RPMs, not sure if that is normal or not. Second, when I put the car in gear, drive or reverse, it makes this awful metallic scraping or clanking or grinding, it only happens under load and between 1500 to 18000 RPMs. And lastly, my check engine light is on, Giving me DTC codes P0420 and P0457. I'm unsure if the codes have anything to do with the noises I'm getting while driving. Any insights would be greatly appreciated. Thanks for your time.


  • thecardoc3thecardoc3 Member Posts: 5,631
    The noise you are hearing is something that you just have to get occurring and search for while it's making the sound. Things like exhaust heat shields can make noises like you are describing but you need to prove it.

    The P0457 is a large evaporative emissions system leak that was detected after a refueling event. The system pulls a vacuum (approximately 10in in water, which is about 1/4 of an inch mercury) with the cannister vent valve closed to perform the large leak test and fails to achieve that much vacuum. The fuel tank and cannister system will need to be tested for a leak (s).

    The P0420 is a Catalyst Efficiency test failure. If there are no exhaust system leaks, and the O2 sensors are working correctly then it's very likely that you will need a new catalyst.
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