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mrcool.com
21
Troubleshooting
Error Codes and Solutions
Turn off the unit, use a multi-meter to
check if the thermistor is conducting.
If E3 exists while the thermistor is
conducting, change the MAIN
CONTROL BOARD.
If you should experience a problem with the water heater, please refer to the following
chart for possible remedies. Error codes that appear on the front panel display are explained
in the following section. For minor problems or issues, resetting the water heater may resolve the issue. To
reset the water heater, press the
POWER
button on the front panel, or turn off the faucet and then back on.
Error
Code
Description
Cause
Solution
E0
E0 Displayed
Accidental Flame
Lost
Flame Signal
Detected Before
Ignition
Thermistor Open
Circuit*
Outlet Water
Temperature
Exceeds 185°F (85°C)
For Over 3 Seconds
Outlet water temperature
sensor open or has
short-circuited.
Ensure temperature sensor is properly
connected. If connection is good, change
the sensor.
If error still occurs change the MAIN
CONTROL BOARD.
Gas has run out during
combustion or no
pressure in the pipeline.
Increase the gas supply pressure to the
required value.
Replace the gas valve.
Replace the sensor.
Open circuit formed
between flame sensor
and the burner or the
heat exchanger before
ignition.
Unplug the flame sensor from the
MAIN CONTROL BOARD, with the
power on, but burner off.
•
If E2 persists
, change the MAIN
CONTROL BOARD.
•
If E2 does not exist
, change the
flame sensor.
Heat exchanger outlet
water overheated.
1. Check if there’s debris or dirt on the
filter of the water inlet. If so, clean
the filter (refer to the Clean the inlet
water filter section).
2. Check the BWF value (refer to the
section regarding the Information
interface for after-sales), if it exceeds
0.4 GPM, check the HE, if the CB error
can be searched from HE, change the
bypass water valve.
1. Check if there’s debris or dirt on the
filter of the water inlet. If so, clean
the filter (refer to the Clean the inlet
water filter section).
2. Check the BWF value (refer to the
section regarding the Information
interface for after-sales), if it exceeds
0.4 GPM, check the HE, if the CB error
can be searched from HE, change the
bypass water valve.
Outlet hot water
overheated.
E1
E2
E3
Thermistor failure.
Temperature sensor failure.
E4
Gas valve operation
is unstable.
* The unit will not automatically restore while this error code is displayed. Press power off and then on to
manually restore the unit.
