Autel Autolink AL301 [5/109] Obd ii readiness monitors

2.4 OBD II Readiness Monitors

An important part of a vehicle’s OBD II system is the Readiness

Monitors, which are indicators used to find out if all of the emissions

components have been evaluated by the OBD II system. They are

running periodic tests on specific systems and components to ensure

that they are performing within allowable limits.

Currently, there are eleven OBD II Readiness Monitors (or I/M

Monitors) defined by the U.S. Environmental Protection Agency

(EPA). Not all monitors are supported by all vehicles and the exact

number of monitors in any vehicle depends on the motor vehicle

manufacturer’s emissions control strategy.

Continuous Monitors -- Some of the vehicle components or systems

are continuously tested by the vehicle’s OBD II system, while others

are tested only under specific vehicle operating conditions. The

continuously monitored components listed below are always ready:

1）Misfire

2）Fuel System

3）Comprehensive Components (CCM)

Once the vehicle is running, the OBD II system is continuously

checking the above components, monitoring key engine sensors,

watching for engine misfire, and monitoring fuel demands.

Non-Continuous Monitors -- Unlike the continuous monitors, many

emissions and engine system components require the vehicle to be

operated under specific conditions before the monitor is ready. These

monitors are termed non-continuous monitors and are listed below: