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Monitors

Your vehicles PCM checks to make sure that it's emmision systems are operating correctly. Each of these systems has it's own "Monitor". An example of a monitor would be Catalyst Efficiency. This monitor watches over your vehicles Catalytic Converter System.

Monitors can be either Complete or Incomplete. Being Complete means that all the tests required to pass or fail the Monitor have been run. Sometimes the results of these tests can be seen in the PCM's Mode6 data.

Monitors can also be Pass or Fail. Pass simply means that all the required tests needed to prove the system is functional have met the required criteria. Fail means that one or more of the tests did not meet the required criteria.

Monitors may also be labeled as Continuous or Non-Continuous. To be Continuous means that it is running all the time whenever the vehicle is. Non-Continuous monitors have to meet certain criteria before their tests may be run. 

Not all cars have all monitors, and some early OBD2 vehicles may actually clear data when the ignition is turned off.

Here is a screenshot showing the state of the Monitors on a Land Rover Discovery. Notice they are all complete. They are all also green which means they pass. The greyed out ones are not used by this vehicle. The top three although not indicated are continuous and the rest are non-continuous.

Notice that the Escan is able to read them once or continuously until they are all complete, the latter being the default upon startup of the tool. This is a unique feature to the tool that others don't have.
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