Which lamp indicates that an active regeneration has been initiated and the exhaust temperature is elevated beyond the threshold?

• A. High Exhaust Temperature Lamp (HEST)
• B. Malfunction Indicator Lamp (MIL)
• C. Check Engine Lamp
• D. Stop Engine Lamp

Answer: (A)

The situation tested here is recognizing an indicator that shows regeneration is actively happening and that exhaust temperature has risen above a safe threshold. The High Exhaust Temperature Lamp is the one that signals this specific condition: when the diesel particulate filter begins an active regeneration, the exhaust temperature climbs, and this lamp lights to warn the operator that regeneration is in progress and the exhaust is hotter than normal. The other lamps serve different purposes—Malfunction Indicator Lamp and Check Engine Lamp point to engine or emissions faults, not a normal regeneration event, and the Stop Engine Lamp signals a critical fault requiring immediate engine shutdown.