Service Handbook

10 • Condensing Models: On-Demand Water Heater Service Handbook
TROUBLESHOOTING
Error Codes
All units have self-diagnostics for safety and convenience when troubleshooting.
If there is a problem with the unit, a numerical error code will display on the TM-RE42 Remote Controller (if installed) or on
the temperature controller of indoor models. Installation-related problems may also produce an error code. If the remote/
temperature controllers are not working, the green LED on the computer board will flash a code pattern. (The green LED is located
just above the DIP switches as shown in Figure 3.)
Table 2: Error and Flash Codes
ERROR CODE GREEN LED ON
COMPUTER BOARD
SYMPTOM OR ISSUE TROUBLESHOOTING PROCEDURE
031 One Flash Incorrect DIP switch setting Incorrect DIP Switch Settings, p. 12.
101 Five Flashes Abnormal Combustion
(lockout is imminent)
Abnormal Combustion, p. 12.
111 or 121 Three Flashes Ignition failure / Loss of flame Ignition Failure / Flame Loss, p. 12.
311 Two Flashes Outlet thermistor failure Outlet Thermistor Failure, p. 13.
321 Two Flashes Inlet thermistor failure Inlet Thermistor Failure, p. 13.
341 Two Flashes
Exhaust thermistor failure
(indoor models only)
Exhaust Thermistor Failure, p. 14.
391 Two Flashes Air-fuel ratio rod failure
Air-Fuel Ratio Rod Failure, p. 14.
Figure 3. Green LED on Computer Board
Figure 4. TM-RE42 Remote Controller
(Continued on next page.)