2019 Western star 5700, Hot exhaust light flashes at idle

Betting you idle a lot. Set idle to 900 anytime your doing extended idle.
Probably stopped truck during a regen that was happening going down the road.
If it keeps it up probably needs to go to dealer for diagnosis and May have a sensor or 2 not reading correctly. Haven’t had mine ever do that in over 800k miles.
Neither one of my western stars. But they only idle 3 min to warm up and 3 to cool off that’s it

 

If surging at idle might be the fuel quantity valve back by fuel pump.. will cause it to surge. Anytime you do extended idle you need to run up to 900 rpm to keep the cyl temps snd pressure up. Still going to plug the face of dpf but high idle will help.