What is the initial step a vehicle owner should take before an emissions test?

Before undergoing an emissions test, it is crucial for a vehicle owner to ensure that the On-Board Diagnostics (OBD) system is functioning properly. The OBD system monitors various components of a vehicle's emissions control system. If the OBD system detects a malfunction, it can trigger a 'check engine' light, indicating the presence of issues that could lead to increased emissions.

Having a functional OBD system is vital because emissions tests often include an evaluation of the data that the OBD system provides. An inoperative OBD system may result in a failed test, regardless of the vehicle's actual emissions performance. Therefore, confirming that the OBD system is operating correctly is an essential step before the test, ensuring that the vehicle meets the necessary emissions standards.