Why must OBD-II readiness monitors be complete before an emissions test?

• A. They verify that emissions control systems are functioning and pass; monitors must be complete for pass.
• B. They indicate battery health for the test.
• C. They determine proper tire pressure for emissions.
• D. They provide maintenance schedule.

Answer: (A)

OBD-II readiness monitors are the built-in self-tests that run to confirm the emissions-related parts of the vehicle are working properly. For an emissions test, the authorities rely on these tests being completed and reported as ready because that proves the emissions control systems have been checked and aren’t currently showing faults. When all the required monitors have finished their checks, it indicates the vehicle has gone through the necessary drive cycles and the data reflect actual emissions performance. If monitors aren’t complete, the test result can be inconclusive or fail because the system hasn’t proven the emissions controls are functioning correctly.

Other options don’t fit because readiness monitors aren’t about battery health, tire pressure, or maintenance scheduling. Those are separate checks or systems and do not determine whether the emissions controls have been validated.