51 Page
-Fault Analysis of Error Codes-
If the error code is displayed on the computer board of the water heater or the controller, please check
the following. After checking, consult with the manufacturer.
Troubleshoong
Owner's Guide
Remote
Green
LED
Malfunction
description
Diagnosis
031
One Flash
Incorrect DIP switch
setting
Check the DIP switch settings on the PCB (Part #701).
101
Five Flashes
Warning for the “991”
error code
Check the gas type of the water heater.
Check if there is any blockage in the intake air and/or
exhaust.
Check if there is enough distance between the exhaust
and air intake terminals.
Check the altitude/elevation of area of where the water
heater is installed.
Check if there is grease and/or dirt in the burner (Part #101)
and the fan motor (Part #103), especially if the water heater
has been installed in a contaminated area.
111*
Three Flashes
Ignition failure Check if the Hi-limit switch (Part #412) is properly
functioning.
Check for connection/breakage of wires (Part #008, 413, 708,
709), burn marks on the computer board (Part #701), and/or
soot on the flame rod (Part #107) and the ignitor (Part #108).
Ensure that the gas supply is turned on. If your water
heater has been properly converted to use propane,
ensure that the tank is not empty.
Check if there is a buzzing spark ignition sound coming
from the burner (Part #101) when water heater prepares
for combustion.
Listen for the double “clunk” sound coming from the gas
valve assembly (Part #102) when the water heater goes
into combustion.
Check if there is leaking from heat exchanger (Part #401).
121*
Three Flashes
Loss of flame Check if the Hi-limit switch (Part #412) is properly
functioning.
Check for connection/breakage of wires (Part #008, 413,
708, 709), burn marks on the computer board (Part #701),
and/or soot on the flame rod (Part #107) and the ignitor
(Part #108).
Ensure that the gas supply is turned on. If your water
heater has been properly converted to use propane,
ensure that the tank is not empty.
Check if there is leaking from the heat exchanger (Part #401).
311*
Two Flashes
110U & 310U:
Outlet thermistor
failure
510U:
Heat exchanger
thermistor failure
Check for connection/breakage of wires and/or debris on
the thermistor (Part #407, 408, 411, 713).
321*
Two Flashes
Inlet thermistor failure
331*
Two Flashes
Outlet thermistor
failure
(510U model only)
391
Two Flashes
Air-fuel ratio rod failure Check for connection/breakage of wires (Part #709) and/
or soot on the AFR rod (Part #107).
441
Two Flashes
Flow sensor failure
(Only Easy-Link &
Multi-Unit System)
Check for connection/breakage of wires and/or debris on
the flow sensor impeller (Part #402).
Check water filter. Ensure isolation valves are open.
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