: Failed smog question

03-16-12, 11:28 PM
Hey guys I recently failed my smog test. The car is putting out a lot of brown smog. My mechanic originally said the smog was blue and gassy smelling. He changed some bad spark plugs and the connecting wires and now the gas smell seems to be gone but it is still smogging as much just its brown. He is thinking the catalytic converter next, what would you guys think?

03-18-12, 11:01 AM
We need to know what kind of car.