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p0420

  1. Stalled then Crank No Start

    Problems and Service
    I have a Cobalt LT 09 auto trans that had been stalling randomly and had a few misfires. I get it home to change the spark plugs and coils, the car stalls and then wont star back up again. When I ran the codes; intake cams, exhaust cam sensor, and a misfire. I have replaced the exhaust cam...
  2. P0420 Code

    Problems and Service
    this has been the year of codes for me. evap and 02 sensores and now cat issues. on 2 cars. i have a 06 2.2 auto cobalt 125k on it. and this code came up p0420 and i ran a ton of tests using the HF scanner. the cat runs at 700 rpm 900 deg at 4k 1200 deg. i did an ir temp and in front of cat...
  3. P0420 - Running Rich

    Problems and Service
    I've been getting the P0420 code (Catalyst System Efficiency Below Threshold ( Bank 1)) and the System too Rich Code. I recently replaced my cylinder head due to burn valves causing misfires and running too rich. I have replaced all 4 injectors, spark plugs, O2 sensors, catalyst convertor...
  4. Gutting Catalytic Converter

    Engine Mods
    Has anyone here ever gutted a catalytic converter? My car has been throwing a P0420 Catalyst System Efficiency below threshold code for a while now, gonna try gutting my cat to see if it helps at all. Has anyone ever done it before that can give me tips? Or is there a way to clean it that is easier?
  5. P0420-After Complete Exhaust Replacement

    Problems and Service
    A few months ago, my car threw the TC P0420. I didn't have the money to deal with it then, but over the last 6 weeks, I've been trying everything I can to no avail. First, I took it to the shop. They charged me 400 for an upstream sensor. CEL came back on. Then, they said I had to replace the...
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