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downstream o2 sensor
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  1. The 7th Generation
    At 313K miles (2007 4CYL Accord SE) my check engine light came on. There was a single DTC: P0420 Catalyst System Efficiency Below Threshold Generally speaking this code indicates a bad catalytic converter, but I went through some diagnosis to try to make sure before buying an expensive...
  2. The 7th Generation
    At 303k miles I had a check engine light and read code P0139: I cleared the codes, and after 3k more miles, I still had no check engine light. However, since I have >300k on the o2 sensor, I decided to change it anyway. It is a pretty simple exercise, but I included some pictures below...
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