Question

3. Technician A says that on-board self-diagnostics test mode procedures should be conducted on a cold engine. Technician B says that many diagnostic trouble codes (DTCs) will monitor items only when the engine control system is in closed loop.

Answer 1

Technician B

Step-by-step explanation:

on-board self-diagnostics test mode procedures should be conducted on a warm engine since many DTCs only monitor in closed loop. Therefore, technician A is wrong. Many DTCs will monitor items only when the engine control system is in closed loop. Closed loop operation requires the engine to reach a certain operating temperature before it can be entered. Therefore, technician B is correct.