i found that the nuts that hold the downstream 02 sensor on the pipe rusted completely off. could air leaking in cause P0420? i put hose clamps around it to hold it on. the light is still on after a few trips. putting new nuts and gaskets on eventually.
check engine light is on , my code reader says P0420. on 2001 Toyota Tacoma
yes an air leak could cause this issue reseal 1st and see what happens
yes it could