P0541 is "Low voltage on the #1 intake air heater relay". It's set when the signal from the #1 intake air heater output does match the signal from the #1 intake air heater feedback. Possible causes are:
-Loose connection
-Intake air heater relay failed
-signal circuit open from relay to ECM
-signal circuit shorted to ground
-ECM
This has nothing to do with your installation of the torque tube (I assume there is no electrical connection between the tube and the grid heaters).