Smog check rules regarding a vehicle's catalytic converter were tightened up a bit in 2014. A smog check technician must now inspect for a catalytic converter's EO (executive order) number. The EO number (also know as CARB number or Executive Order) is assigned by the California Air Resources Board to California compliant aftermarket emission components. If EO numbers are not found on any CAT being inspected, or EO number found but not matching the numbers required for the vehicle the CAT is installed on, the vehicle will fail the smog check for an "emissions tamper".
