TROUBLESHOOTING
TROUBLESHOOTING
TROUBLESHOOTING
12 • On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models
ERROR CODE
GREEN LED ON
COMPUTER BOARD
SYMPTOM OR ISSUE
321 Two Flashes Inlet thermistor failure
331 Two Flashes
Outlet thermistor failure
(540 model only)
341 Two Flashes
Exhaust thermistor
failure
(indoor models only)
Two Flashes
Air-fuel ratio rod failure .
441
Two Flashes
Flow Sensor Failure
(Easy-Link or Multi-Link
System)
510
Six Flashes
Abnormal main gas
solenoid valve (MV)
.
551
Six Flashes
Abnormal gas solenoid
valve (SV1, SV2, and/
or SV3)
.
611 Four Flashes Fan motor fault .
651 Four Flashes
Flow adjustment valve
fault (Easy-Link or Multi-
Link System)
.
661 Four Flashes
Bypass valve fault
.
701 One Flash
Computer board fault
.
711 One Flash
Gas solenoid valve drive
circuit failure
.
721 Six Flashes False flame detection .
741 N/A
Miscommunication
between water heater
and remote controller
.
751 N/A
Miscommunication
between water heater
and temperature
controller (Indoor
model only)
.
761 N/A
Miscommunication
between units in an
Easy-Link or Multi-Link
system. (540/T-H3 Only)
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