Instruction manual
73
SECTION XV: TROUBLESHOOTING (continued)
b.  If the Boiler Control detects an error it will ash "Err" (boiler control error) followed by a number. Use this text and 
number to identify the boiler problem and corrective action in Table 11 below. 
Display Status Recommended Corrective Actions
Err  Temperature Sensor Fault
Temperature sensor failure, wire harness loose or shorted connection or control 
hardware failure:
- Check sensor is securely attached to boiler control
- Check that sensor wire is not damaged
- If secure and in good condition, replace sensor
- If problem persists, replace control
Err 2 Communication Fault
Enviracom terminal is shorted to ground or line voltage. 
- Check wiring to EnviraCOM terminals 1,2 and 3. Wiring to external EnviraCom 
 device is incorrect.
Err 3 Internal Hardware Fault
Error detected with AC power supply frequency or boiler control failure. Cycle power to 
the control. Replace control if problem persists. 
Err 4 Burner Output (B1) Fault
B1 output sensed powered during safety output relay check sequence or un-powered 
during running, or powered in idle in combination with water temperature above 264°F 
limit. Cycle power to the control. Replace control if problem persists.
Err 5 Line Voltage Fault (< 80 Vac) AC voltage out of specication high or low; check L1, L2, 110 VAC. 
Err 6 Fuse missing
Internal fuse is blown or missing. The fuse protects the Aquastat from miswiring the L1 
and L2 on Oil Primary. When the Oil Primary is correctly wired the fuse is useless and 
not detected. If Primary is wired incorrectly the fuse is blown out and Aquastat report 
error 6. EnviraCOM message is sent when the wiring is xed and the error disappears 
to indicate the end of the error state. Check wiring and replace fuse. 
Err 
User settings lost, (reset to 
factory defaults)
Warning: Generated if user adjustments are lost and the device uses factory default 
values. Error is cleared by entering and exiting the Adjustment mode. Replace control 
if problem persists. 
Err 
Manual Reset Lockout 
(resettable)
Set if Err 4 was invoked four times in a row. Check wiring and clear Lockout by 
pressing all three user keys for 30 seconds.
TABLE 11: BOILER CONTROL ERROR NUMBERS










