friend comes to me today about failing smog. so here is a list of codes
BUMP any ideas people. friend is having the same issue...

p0420 cat efficency below treshold (bank 1)
p0302 misfire detected (cyln 2)
p0303 misfire detected (cyln 3)
p0304 misfire detected (cyln 4)
p0305 misfire detected (cyln 5)
p0306 misfire detected (cyln 6)
p1705
p0300 Random/Multi Misfire Detected


I'm sure all these codes are because of the misfire. Where do I start? New plugs, Wires, Cap, Rotor... If this does nothing then what maybe replace the dizzy???

 

with all those miles, I'd say to try new plugs first.
Then clear the codes and try again// 2 drive cycles for most emission codes to reappear.

P1705 Gear position switch problems, or trans control module.....I'm pretty sure.