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.

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Engineering

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9 July, 19:43

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.

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Angelique Duke · Answer 1

Technician B

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.