What should you do if a vehicle stalls while performing a one-speed idle test?

In the context of a one-speed idle test, if a vehicle stalls, the best course of action is to restart the car and allow it to idle for 30 seconds before continuing the test. This step is important because it gives the engine a moment to stabilize, ensuring that any readings taken afterward are accurate and reflective of the vehicle's emissions under normal operating conditions.

When a vehicle stalls during an emissions test, it could indicate an underlying issue that needs to be addressed. Restarting the vehicle and waiting also helps to clear any potential error codes and allows the engine management system to reset, which is essential for obtaining valid emissions data.

Options like waiting for the vehicle to restart automatically or disconnecting the battery are not practical or advisable actions in this situation. Advising the owner without taking corrective action may overlook the opportunity to collect meaningful emissions data. Therefore, restarting the vehicle and giving it some time before continuing is the most effective approach.