Low coolant the first thing to check.
Any history on fuel filters ? Lift pump ? Is this a 24 Valve engine ? ( Sorry to ask , but I'm unsure of when the M/H industry went to the 24 V engine.) Cummins would be the shop to check things out , but other truck shops should be able to check for codes.
Intermitant codes in the system, may migrate out when the light goes out, ( the computer thinks the problem is fixed ) or be dropped when the key is turned off. So the best time for a scan would be , when the light is on, or after the light has been on but before the engine is turned off.
This may be an issue that you can't get a handle on unless you can scan the system on the road with your own laptop as it happens .