1996 Buick Regal 3.1L

I had a check engine light. Code read as 0420 (??) Auto store said cylinder misfire. I knew I needed a tuneup, so I changed plugs, wires, all three distributors, and PCV valve. Car starts and idles okay, but when I put in gear (D or R) the car sputters, chokes, and stalls. I can’t find any vacuum lines disconnected. Any ideas what the problem might be?

1 thought on “1996 Buick Regal 3.1L”

  1. P0420 : Catalyst System Below Threshold

    Code P0420 will set if the PCM detects a level of post CAT HO2S activity that indicates catalyst is no longer operating efficiently.

    The most common cause for this code is the failure of the catalytic converter.

    With your symptoms and the Code P0420, I would suspect a clogged catalytic converter.

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