California Smog Check Inspector Practice Test

What should a technician do if there is a "HC Hang-Up" error?

1. Increase the idle speed

2. Change the fuel filter

3. Find and repair the leak prior to performing an inspection

4. Replace the entire exhaust system

The correct answer is: Find and repair the leak prior to performing an inspection

When a technician encounters a "HC Hang-Up" error, it indicates that there may be a high level of hydrocarbon emissions that the vehicle is unable to clear effectively. This situation often arises from leaks in the fuel and exhaust systems, as well as faults in components of the vehicle's emission control systems. The correct action in this scenario is to locate and repair any leaks prior to performing an inspection. Addressing leaks is critical because they can lead to an inaccurate reading of the vehicle's emissions and may present underlying issues that need to be corrected for the vehicle to comply with smog regulations. By repairing leaks, the technician not only helps ensure the vehicle meets emissions standards but also contributes to better overall engine performance and efficiency. This proactive approach helps to minimize the chances of future failures in emissions tests as well. Others listed, such as changing the fuel filter or replacing the entire exhaust system, might not directly address the immediate issue indicated by the "HC Hang-Up" error, while simply increasing the idle speed does not rectify underlying problems related to emissions.