A professional who conducts and evaluates tests on vehicles to check exhaust emissions. Respnsibilities include:

• Reviews instructions to determine details of test to be performed.
• Drives vehicle over dynamometer.
• Records identifying data.
• Performs dwell, timing and idle speed tests using gauges, evaluates performance and adjusts performance to manufacturer's specifications.
• Adjusts dynamometer settings to vehicle specifications and connects instrument sensors to exhaust system.
• Starts and operates vehicle according to test program, compares performance with specifications and records results.
• Calibrates, cleans and maintains test equipment and recording devices.
• May diagnose and repair vehicle malfunctions.
• May install smog-control device on tested vehicle.