California Smog Check Inspector Practice Test

What should occur when the EGR is opened during idle?

1. Check upper and lower radiator hoses, wait for fan to cycle

2. Decrease engine temperature significantly

3. Increase engine RPM dramatically

4. Activate the vehicle's air conditioning system

The correct answer is: Check upper and lower radiator hoses, wait for fan to cycle

When the Exhaust Gas Recirculation (EGR) system opens during idle, the expected behavior of the engine involves certain changes in its operation. The EGR system is designed to recirculate a portion of the engine’s exhaust gases back into the intake manifold, which helps reduce Nitrogen Oxide (NOx) emissions by lowering the combustion temperature. The correct response indicates that during the EGR operation, it is important to monitor the upper and lower radiator hoses and check for any cooling system changes, including waiting for the cooling fan to cycle. This is because the EGR process may lead to increased exhaust temperatures, which can affect the engine's cooling system. By ensuring that the cooling system components are functioning properly, inspectors can determine if the vehicle is maintaining appropriate operating temperatures while the EGR is actively recirculating exhaust gases. Other options, such as lowering engine temperature significantly or dramatically increasing engine RPM, suggest outcomes that do not align with the operation of the EGR during idle. The EGR's purpose is to recirculate exhaust rather than create radical changes in engine temperature or idle speed. Similarly, activating the air conditioning system is unrelated to the function of EGR and is not influenced by its operation at idle. Thus, the