P0420 Toyota Corolla 2004


Hello I have a toyota corolla 2004 with the engine light flashing. I took the car to the dealership to read the fault codes.

It says P0420 catalytic efficency low.

they deleted the fault codes and I run around 50 km and the light is on again

do you have any tips how to fix this problem?

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Josh 2 months 1 Answer 223 views Member 1

Answer ( 1 )

  1. Selleen Diagnostic Technician

    Hi josh.

    The fault code P0420 is telling you that the catalytic converter efficency is low.
    Most common is that the catalytic converter is worn out.
    Could also be lambda sensor upstream or downstream.

    NOTE: you could have other things like misfires, oil burning that has destroyed the catalyst.

    For more detailed fault diagnostics, repost!


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