my check engine light is on ,has been for a while, now my car failed smog test

you need to have circuits tested to start with and if good test sensors.are they unpluged or have corrision on them

take out the MAF, clean it inside , the 2 resistors , spray in brake cleaner, use "Q" tip to wipe off, let it air dry, 10-15 minutes. then disconnect battery or reset codes with code checker, car should run fine and chk light out. I dont know anything about smog test, we don't have that here in Canada. SORRY