the Record Straight on Readiness
Monitors and On-Board Diagnostics
Monitor Status is NOT the same as Diagnostic Trouble Codes (DTC’s). Readiness
represents whether or not the emissions control system in question has been
evaluated. This evaluation tests for system functionality and, if a problem is
detected, a DTC will be stored in the on-board computer.
Readiness Monitor Status
- What does "Ready" vs. "Not
Ready" status mean?
What is the most common reason monitors are "Not
- Where is Readiness Monitor Status on the Vehicle
Inspection Report (VIR)?
- Changing the monitor(s) to "Ready"
- If the vehicle has DTC's stored, and the MIL is
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the OBDII system has checked this emissions control system.
does "Ready" vs. "Not Ready" status mean?
-Not Ready - the OBDII system has NOT checked this emissions control
-N/A or N/S - the OBDII system is not required to check this emissions
Emissions Tests Results section of the VIR shows the status of each readiness
is Readiness Monitor Status on the Vehicle Inspection Report (VIR)?
-REMEMBER: The vehicle will FAIL the OBDII inspection if more than two
(2) monitors are "Not Ready".
Engine On: PASS
-In order to
get the OBDII system to set the monitors to “Ready”, the vehicle needs to be
driven through a drive cycle/drive trace.
the monitor(s) to "READY"
-If you don’t have access to drive cycles/drive traces, they should be
available from a qualified service technician or dealership.
-With a generic OBDII scan tool*, verify the monitors are “READY” before
returning the vehicle to the customer.
manufacturer specific scan tools must be in the global OBDII or generic OBDII
mode to display readiness monitor status.
vehicle will need repairs to correct the malfunction before it will pass the
the battery is the most common reason why monitors are “Not Ready”
reasons for disconnecting the battery are:
*tune-ups and other engine repairs
*dead battery replacement
*car radio installations
*car alarm installations
the vehicle has DTC's stored, and the MIL is commanded on:
-If you've cleared the DTC's (using a scan tool or disconnecting the battery),
monitors will reset to "NOT READY".
-Driving the vehicle through the drive cycle/drive trace will set the monitors
back to "Ready" and verify that the repairs were effective.
-With a generic OBDII scan tool, verify the monitors are "READY"
before returning the vehicle to the customer.
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