Why is control of primary heat abnormal on my Graco Reactor E-10hp?
- JJoshua SmithSep 23, 2025
Abnormal control of primary heat, such as high temperature overshoots or intermittent E01 errors, can be caused by dirty thermocouple connections. Examine the connection of thermocouples to the long green plug on the heater control board, unplug and re-plug the thermocouple wires, cleaning off any debris. Another cause is the thermocouple not contacting the heater element. Loosen the ferrule nut, push in the thermocouple so the tip contacts the heater element, and tighten the ferrule nut 1/4 turn past tight. Other potential causes include a failed heater element, signal failure from the thermocouple, or the thermocouple being wired incorrectly.









