HEST light on too often...

[Brock]

08 Prostar with a 871. it's got a new turbo on it and I just did the egr tuneup to try and correct this issue to no avail.

My hest light comes on when I slow down darn near every other time so I see it 6 or so times a day. most times it goes out once I gain speed but once a day it'll stay on for a half hour.

Engine is a stock 500, dpf and doc cleaned in November but during my tuneup I did find my doser to be plugged to the max

I do not have a pyro or boost guage nor access to insite. going to get a shop to force a regen in coming days.

I haul 140,000lbs but even when empty, it does it.

Amy thoughts?