V-MAC Co-Pilot Operator's Manual 17 High Exhaust System Temperature (HEST) Indicator The High Exhaust System Temperature (HEST) indicator, amber in color, illuminates to alert the driver when engine Exhaust Gas Temperatures (EGT) are high. The HEST indicator will also illuminate during a aftertreatment Diesel Particulate Filter (DPF) parked regeneration event and will turn off after the regeneration is completed and the EGT has returned to normal. For additional information about the HEST indicator, please refer to “Aftertreatment DPF Smart Switch (If Equipped)”, page 21. W3036496 High Exhaust System Temperature (HEST) Indicator