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
time. 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.
2.6 OBD II Definitions
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
2.5 OBD II Monitor Readiness Status
OBD II systems must indicate whether or not the vehicle’s PCM’s
monitoring has completed testing on each emission component.
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