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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
leastoneovernight-offperiod.Forspecicinformationongettingyourvehicle’s
OBD monitor system ready, please consult your vehicle owner’s manual.
– OBDII terminology for the on-board
computer that controls engine and drive train.
– 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.
Undercertainconditions,thedashboardlightwillblinkorash.Thisindicates
asevereproblemandashingisintendedtodiscouragevehicleoperation.The
vehicle onboard diagnostic system cannot turn the MIL off until the necessary
repairs are completed or the condition no longer exists.
–DiagnosticTroubleCodes(DTC)thatidentieswhichsectionofthe
emission control system has malfunctioned.
– Also termed Enabling Conditions. They are the vehicle-
speciceventsorconditionsthatmustoccurwithintheenginebeforethevarious
monitors will set, or run. Some monitors require the vehicle to follow a prescribed
“drive cycle” routine as part of the enabling criteria. Drive cycles vary among
vehicles and for each monitor in any particular vehicle.
–Aspecicmodeofvehicleoperationthatprovidesconditions
required to set all the readiness monitors applicable to the vehicle to the “Ready”
condition. The purpose of completing an OBD II drive cycle is to force the vehicle
to run its onboard diagnostics. Some form of a drive cycle needs to be performed
after DTCs have been erased from the PCM’s memory or after the battery has
