If the vehicle cannot be tested on a dynamometer due to being AWD, which test should you perform for emissions?

When a vehicle cannot be tested on a dynamometer, particularly an All-Wheel Drive (AWD) vehicle, the recommended approach for assessing emissions involves conducting both the idle test and the plug-in test.

The idle test focuses on checking the emissions output of the engine while it is idling. This test can provide valuable insight into the vehicle’s emissions characteristics without the need for it to be driven, which is particularly useful for vehicles that cannot be rolled on a dynamometer due to their drivetrain configuration.

The plug-in test, also known as the onboard diagnostic (OBD) test, evaluates the vehicle's emission control system by connecting a diagnostic scanner to the vehicle's OBD-II port. This allows technicians to read trouble codes, monitor the status of emissions-related systems, and assess the overall functionality of the vehicle's emissions controls, ensuring they meet required standards.

By performing both tests, you can gather a comprehensive view of the vehicle’s emissions performance, ensuring compliance with emissions regulations, even when traditional testing methods like dynamometer testing are unavailable. This dual approach compensates for the limitations of each individual test, as the idle and plug-in tests together provide a more complete assessment of the emissions system.