Lennox Error Code 348

Priority condition: Service Soon Possible cause for alert code 348 is Y2 relay on the applicable system component may have failed. Lennox communicating thermostat sends a Y2 compressor demand to the indoor control requesting it to relay the demand to the outdoor unit. The indoor unit communicating control will verify the presences of 24VAC between the Y1 and C on its terminals. If it does not detects the presences 24VAC, it will trigger alert code 348. Either the furnace pilot relay contacts did not close or the relay coil did not energize. • Possible Y2 relay / stage 2 failure. • Furnace pilot relay contacts did not close or the relay coil did not energize. • No input back to furnace or air handler control.