Hvac False Fault Code on the Control Board

The board was giving a fault code of open aux. limit switch. I temporarily bypassed the switch to see if it would give the same fault code, ruling out a weak/faulty switch. (Btw the air filter was clean) The homeowner called me a couple hrs later saying the heater shut down again. So the next morning I installed a new control board. (caution: loud meter beeps)