Is it true that all vehicles must receive an EGR functional test following the ASM portion of the Smog Inspection?

• A. False.
• B. True.
• C. Only for diesel vehicles.
• D. Only with a failed initial test.

Answer: (B)

EGR function is checked after the ASM portion to confirm the emissions-control system is actually working in every vehicle. The EGR system lowers NOx by recirculating a portion of exhaust gas back into the intake, which reduces combustion temperatures. If the EGR valve is stuck, leaks, or not being commanded by the engine, NOx can rise significantly even if other parts pass inspection. Because EGR performance directly affects emissions, the test is mandated for all vehicles, not just certain types or only when the initial test fails. The test typically verifies that the EGR valve opens and flows as it should, that vacuum and control signals are correct, and that there are no blockages or leaks in lines and passages.