If the high exhaust temp light comes on, drive at highway speeds for an auto regen to resolve the issue efficiently. High exhaust temp lights indicate potential engine problems that can be resolved during driving for optimal performance. Ensure safe driving conditions and address the problem promptly to maintain engine health and efficiency.. When a Diesel Particulate Filter regeneration process begins, the High Exhaust System Temperature HEST lamp illuminates and exhaust gas temperature may reach 1500 degrees F. That's hot enough to ignite and/or melt materials and burn people. The main function of the HEST lamp is to alert the operator of extreme high exhaust system temperatures.
How to fix high exhaust temperature? Discover effective solutions to reduce excessive exhaust heat and improve engine performance. Let's read on.. Cummins High Exhaust Temp Light According to the Cummins engine light identification guide, this is just an advisory light that tells you that exhaust temperatures are higher than normal due to a regen process taking place.