2.5 OBD II Monitor Readiness Status
2.6 OBD II Definitions
OBD II systems must indicate whether or not the vehicle’s PCM’s monitoring
has completed testing on each emission component. Components that have
been OBD II tested will be reported as “OK”. The purpose of recording
readiness status is to allow inspectors to determine if the vehicle’s OBDII
system has tested all the emissions systems. This is handy to know before
bringing vehicle to a state emissions testing facility.
The powertrain control module (PCM) sets a monitor to “OK” after an
appropriate drive cycle has been performed. The drive cycle that enables a
Monitor and sets readiness codes to “OK” varies for each individual monitor.
Oncce a monitor is set as “OK”, it will remain in this state. A number of factors,
including erasing of diagnostic trouble codes (DTCs) with a code reader or a
disconnected battery, can result in Readiness Monitors being set to “INC”
(incomplete). Since the three continuous monitors are constantly evaluating,
they will be reported as “OK” all of the ime. As long as there are no DTCs stored
in memory, the vehicle is running in accordance with the OBD II guidelines. If
testing of a particular supportes non-continuous monitor has not been
completed or not tested, the monitor status will be reported as “INC”
(incomplete).
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.
Powertrain Control Module (PCM) – the OBD II terminology for the on-board
computer that controls the engine and the drive train.
Malfunction Indicator Light (MIL) – Malfunction Indicator Light (Service Engine
Soon, Check Engine) is a term used for the light on the instrument panel. It is to
alert the driver and/or the repair technician that there is a problem with one or
more of vehicle’s systems and may cause emissions to exceed federal
standards. If the MIL illuminates with a steady light, it indicates that a problem
has been detected and the vehicle should be serviced as soon as possible.
Under certain conditions, the dashboard light will blink or flash. This indicates a
severe problem and flashing is intended to discourage vehicle operation. The
vehicle onboard diagnostic system can not turn the MIL off until necessary
repairs are completed or the condition no longer exists.
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