Background

Most vehicles are equipped with a single exhaust pipe. However, some vehicles have more than one exhaust pipe exiting the vehicle. If this is the case, then dual exhaust probes will be necessary. Both exhaust pipes will need to be sampled at the same time during the test. If a vehicle has dual exhaust, insert the dual probes using the same method. Never plug a pipe to test the other, as it is extremely dangerous to people and vehicles.