P0031 2004 Toyota Corolla -

Question

instant p0031 code flies as soon as I hit the gas peddle. already replaced 02 sensor, checked harness pin-to-pin from 02 plug to ECM.
I want to make sure it is the ECM before I spring for an ECM $$$$$$$.
anything left? Can any 04 corolla ECM work and fix the MIL

Answer 1

check the EFI relay 

see diagnostic procedures below