Daikin E401 (SS)~E402 (DSS)~E403 (RS)~E404 (DRS-optional)

Alarm Logic	E401 Supply air sensor (SS) is not functioning correctly E402 Supply air sensor for Data-recorder (DSS) is not functioning correctly E403 Return air sensor (RS) is not functioning correctly E404 Return air sensor for Data-recorder (DRS optional) is not functioning correctly
Possible Causes	Device malfunction Sensor failure / Controller failure / Broken wire / Connector disconnected / short circuit
Trouble Shooting	1. Check connector CN43 and make sure it is properly installed	1. Proceed to the next step if the alarm still occurs
	2. Remove CN43 connector and check sensor resistance	2. Sensor is functioning if it matches the resistance and temperature sensor characteristics table (refer to page 6-2 Check CPU board)
Controller Action	E401 Abnormal SS ~ 1st 1st backup by DSS ~ 2nd 2nd backup by RS–2°C E402 Abnormal DSS ~ backup by SS E403 Abnormal RS ~ 1st backup by DRS (optional) ~ 2nd backup by SS+5°C E404 Abnormal DRS (optional) ~ backup by RS