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Q: What does this code mean P0420 ? 1997 Chevy Express 1500

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Catalyst efficiency below theashold light is on what does it mean engine light is on and that what it said

My car has 234 miles.
My car's transmission is unknown to me.

Hello - the P0420 code means the catalytic converter has lost it’s ability to burn residual fuel. This could be due to an engine condition that has clogged the catalyst, or a failing oxygen sensor that is not adequately monitoring exhaust gases, and feeding bad data to engine management. The result is the same, inadequate catalytic converter functionality. I would recommend a Check Engine inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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