I have a friend with an 03 lby 2500HD ,it is getting hot while towing ,shown codes are as follows P0621 ,& P2229, The First Is The Alt Control Circuit , & The Second Is The Baro Sensor Circuit , Could Someone Tell Me What This Means?The Alarm Came On And The Temp Got To 250?

Sorry LB7.

Don't know if a bad baro sensor could cause overheating or not, but the ECM wouldn't know what the boost level is, I quess.

Check out threads on the DEXCOOL. Might need a flush and refill.

worth looking into ,Thanks