Tech confirmed E1 and E2 on thermostat 4. Found the error codes online refer to heat failure and cooling failure. RTU4 has a 2 flash lockout error at RTRM board. Blower is running. System is not heating. Duct detector does not appear to be tripped. Tech reset lockout with power cycle and ran through each mode of operation at test pins. Recorded refrigerant pressures and amp draws. System has a two stage compressor and a single stage compressor and heat strips. Four heat stages total. Tech was unable to duplicate lockout. System is back operating in heat. No charge for callback.