my check engine light will not go off.i have disconnect the postive cable,to reset. it went off last year and then came back on. the problem occure is every day. i have two code p770. which is the soloneid switch sticking . i had aamco to replace it last year but it is still reading the same code. also the second code is p420. how do i pass my emission test
check engin light on on 2003 Toyota Corolla
P0420 is low catalytic converter efficiency. It is an expensive code to fix. Usually it is a sign that the cat. convt. has got lazy but it is sometimes a O2 sensor/air fuel ratio sensor problem.
you need to have it fixed. get a diag and repair on the trans code and a shop for the code for the cat. clearing the code does not fix it. you need to address it before it becomes a bigger problem.