Why does my engine light come back on after replacing the catalyst converter

Question

I had my car serviced two months ago for a P0420 code which the service center said my catalyst converter was not working properly  Now the service engine light is back on with the same P0420 code. What could be wrong now, and should this repair be covered under warranty after failing so soon?

Answer 1

Hi there,

This could be the result of a poorly running engine, a leak in the exhaust system or a faulty rear O2 sensor. This should certainly be covered under warranty especially if the problem is the converter itself.