Ready
The monitor has completed the evaluation required by the vehicle’s OBD strategy. A ready monitor can still have diagnostic information associated with it; readiness alone is not a pass/fail diagnosis.
OBD MONITOR STATUS“Not ready” is a state.
“Not ready” is a state.
Not a failed-part diagnosis.
Readiness tells you whether an OBD monitor has completed its self-check. It does not, by itself, prove that the monitored system has failed.
Readiness status helps explain monitor state; it does not replace code evidence, vehicle-specific criteria, or current inspection rules.
- 01PreserveCodes, monitor states, and recent work
- 02ExplainReady, not ready, or not applicable
- 03VerifyExact vehicle enable conditions
- 04InspectCurrent local emissions rules
- 05ContinueDiagnose without erasing evidence
Follow the sequence, stop when evidence changes the path, and verify the exact vehicle information before acting.
QUICK ANSWER
✓ Government sourceWhat the three common states mean
Not ready
The monitor has not completed its evaluation. EPA guidance lists reasons such as insufficient operating conditions after a reset, recent battery disconnection or maintenance, vehicle-specific OBD behavior, and other readiness issues.
Not applicable
The vehicle does not support that particular monitor. Monitor availability varies by vehicle and emissions configuration.
DIAGNOSE FIRST
Before trying to “force” readiness
Do not clear codes or disconnect the battery simply to make a warning disappear. That can erase evidence and reset completed monitors.
Preserve scan evidence
Record stored, pending, and permanent diagnostic information plus the monitor states before clearing anything.
Ask what changed
Recent battery work, code clearing, module programming, repairs, or long periods without the necessary operating conditions can affect readiness.
Use exact vehicle information
Manufacturer enable criteria and drive conditions differ. IAR does not invent a universal drive cycle or claim that one routine applies to every vehicle.
Check local inspection rules
Inspection acceptance rules vary by jurisdiction and can change. Verify the current rules where the vehicle is registered rather than assuming a universal number of incomplete monitors is allowed.
SOURCE BOUNDARY
EPA readiness guidance
The source supports readiness-state concepts and general causes of incomplete monitoring. It does not supply a universal manufacturer drive cycle, exact enable thresholds, or current inspection acceptance rule for every state.