Sample dilution can be caused by an exhaust leak, but does not necessarily require exhaust
system repair to inspect the vehicle.
A Smog Check inspection is not intended to sell exhaust work on a testable vehicle. Of course, any time an inspector finds a potential safety hazard, such as an exhaust leak, the inspector should notify the customer and note the problem on all copies of the repair order.
• If there is an opening in the exhaust system that will allow the inspector to safely insert the probe properly without causing damage to the vehicle, the inspector may use it to obtain the sample as long as the opening is downstream of all emission control components (such as a catalytic converter).
If the EIS "Emission Inspection System" is notifying you that there is a sample dilution from excessive holes in the exhaust you should insert the emissions probe into the exhaust opening down stream of the catalytic converter.