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Once the vehicle is running, the OBDII 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:
1. EGR System 5. O2 Sensor Heater
2. O2 Sensors 6. Secondary air
3. Catalyst 7. Heated Catalyst
4. Evaporative System 8. A/C system
OBD II Monitor Readiness Status
OBDII systems must indicate whether or not the vehicle’s PCM’s monitor
system has completed testing on each component. Components that have
been tested will be reported as “Ready”, or “Complete”, meaning they have
been tested by the OBDII system. The purpose of recording readiness
status is to allow inspectors to determine if the vehicle’s OBDII system has
tested all the components and/or systems.
The powertrain control module (PCM) sets a monitor to “Ready” or
“Complete” after an appropriate drive cycle has been performed. The drive
cycle that enables a monitor and sets readiness codes to “ready” varies for
each individual monitor. Once a monitor is set as “Ready” or “Complete”, it
will remain in this state. A number of factors, including erasing of diagnostic
trouble codes (DTCs) with a scan tool or a disconnected battery, can result in
Readiness Monitors being set to “not ready”. Since the three continuous monitors
are constantly evaluating, they will be reported as “Ready” all of the time. If testing
of a particular supported non-continuous monitor has not been completed, the
monitor status will be reported as “Not Complete” or “Not Ready.”
In order for the OBD monitor system to become ready, the vehicle should be
driven under a variety of normal operating conditions. These operating conditions
may include a mix of highway driving and stop and go, city type driving, and at
least one overnight-off period. For specific information on getting your vehicle’s
OBD monitor system ready, please consult your vehicle owner’s manual.
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