High Exhaust System Temperature (HEST) Lamp

A slow (10-second) flash, indicates a regeneration is in progress, and the driver is not controlling the engine idle speed.

A solid illumination indicates potentially hazardous exhaust temperatures at the outlet of the tail pipe if speed is below 5 mph (8 km/h). It does not signify the need for service; it only alerts the vehicle operator of high exhaust temperatures. See the engine operation manual for details.