20 V-MAC Co-Pilot Operator's Manual 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 exhaust EGT has returned to normal. For additional information about the HEST indicator, please refer to “Aftertreatment DPF Smart Switch”, page 24. W3036496 Figure 10 — High Exhaust System Temperature (HEST) Indicator