What should vehicles manufactured between 1996 and 2000 have in terms of OBD readiness?

Vehicles manufactured between 1996 and 2000 are required to meet specific standards regarding On-Board Diagnostics (OBD) readiness to ensure that emissions control systems are functioning properly. During this time frame, it is acceptable for these vehicles to have one readiness monitor that is not checked, meaning that the vehicle can still pass emissions testing as long as all other systems are prepared and at least one readiness monitor is not triggered.

The concept behind this regulation is to allow for some flexibility in the emissions testing process, recognizing that not all vehicle systems may be fully operational or tested at the time of inspection. This aspect of OBD readiness is particularly relevant for older vehicles, where systems may not always be optimal but are otherwise compliant with emissions standards when the majority of monitors show readiness.

In contrast, options indicating that all systems must be ready or that none can be not ready would impose stricter requirements than what was established for that vehicle model year, making those statements incorrect. The notion that at least two systems must be checked does not align with the regulations allowing for one non-checked readiness monitor, which further illustrates why the correct answer is focused on the flexibility permitted for vehicles from that era.