The OBD-II term that refers to the conditions under which a diagnostic test will run is Readiness Monitors. These monitors are internal diagnostic routines that the vehicle’s computer performs to ensure the various emission control systems are functioning correctly. A readiness monitor will only execute when all the necessary preconditions or “enabling criteria” have been met, such as engine temperature, vehicle speed, and load.
Readiness monitors are critical for emissions testing. Vehicles are often required to pass an OBD-II readiness check before they can pass an emissions inspection. This ensures that the vehicle’s emissions control systems are fully operational and that any potential issues are identified. Historically, readiness monitors were implemented to provide a standardized way for technicians and inspection stations to assess the functionality of emission-related systems, preventing false failures due to incomplete diagnostic cycles.
