For the Smog Test: During the visual inspection portion of the smog test the smog technician will be inspecting your vehicle's air injection system. If your vehicle is equipped with a pump air injection system the technician will be checking for the proper connection of the injection system plumbing, all hoses, lines, valves and smog pump.
The smog technician will also examine the air pump belt for proper tension and damage. During your at-home check up ensure all connections are intact and components present. If it appears there are missing parts or open ends seek repair assistance from a certified smog repair station before subjecting your vehicle to the smog inspection.
For vehicles equipped with the pulse air injection system, the technician will only inspect the injection pipes and valves.
Note: During the smog test the air injection system is only visual inspected. The smog technician will not insure the proper operation of this system, rather he or she will only verify that the system is installed and properly connected.
Will aftermarket headers cause my car to fail the smog test?
The answer is yes. Exhaust headers, not to mention the entire AIR Air injection system is an "emissions component". Any modification to the headers, intake manifold, or exhaust manifold, including removal of a "Y" tube from the exhaust pipes (if equipped) is considered an emissions tamper. Your vehicle will fail the smog inspection even before the tailpipe exhaust is checked.
Mufflers: The smog test does not test the muffler. However we don't recommend you take the vehicle in for testing if your vehicle's muffler is broken or has holes in it from damage or rust. It may cause the smog technician problems getting the smog machine to accept testing your vehicle.
Smog machines are calibrated in California every three days, and are designed to not allow the testing of vehicles which emit oxygen levels exceeding a smog machines preset limits. In other words, if your vehicle's muffler has large holes which are allowing oxygen to be vacuumed in with the emissions stream, the test results would have been inaccurate. The smog machine may not allow the inspection to continue and/or fail the smog inspection.