Readiness Monitors

The on-board computer verifies proper function of emissions control systems by performing Emissions Control System Checks under specific conditions defined by the manufacturer (a "Drive Cycle"). Upon completion, each system is flagged as "READY." If not yet completed, it is flagged as "NOT READY." In Arizona, a vehicle will be rejected from emissions testing if more than two monitors report NOT READY (1996–2000) or more than one (2001+).