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There is an adjustment screw under the rubber boot in the back of the machine for the pressure sensor. Set your regulator at the lowest pressure your air system provides and turn the screw until the “Air Pressure” LED on the status tab turns green. Inward should set it to a higher pressure and outward should set it to a lower pressure. (Newer sensors have a 3mm hex bolt, instead of the flat blade)
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Replace the sensor
Reason: There is a short in the circuit.
Find and repair the short.
An extreme solution that my be irreversible would be to cut the wires connecting the female 3.5 mm jack to the ATC control board and use wire nuts or electrical tape to cap them off. As long as the short was past where you cut, you will break the circuit and the ATC control board will see the “open” it needs to operate.