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mrcool.com
Troubleshooting
E5
Fan Failure
Cables not connected.
Fan controller failure.
• Connect the cables.
• If E5 persists, replace the fan.
E6
Gas Valve Failure
Solenoid Failure.
Cables not connected.
• Connect the cables.
• If E6 persists, replace the gas valve.
E9** Fan Failure
Main water valve jam.
EE
Overtime
Operation time exceeds
40 minutes.
Clean the main water valve.
F2
Inlet Water
Temperature
Sensor Failure
Inlet water temperature
sensor open or has
short-circuited.
• Ensure the sensor is connected.
• If the sensor is connected & F2 persists,
change the sensor.
• If F2 persists with a new sensor, change
the MAIN CONTROL BOARD.
C0
Ignition Failure
Gas valve not open.
Air in the gas supply line.
Gas supply pressure too low.
Nozzle blockage.
No signal from flame sensor.
Replace the gas valve.
Attempt to ignite several times to
discharge the air.
Ensure gas supply pressure is within range.
Clean the nozzle.
Change the flame sensor, if C0 persists,
change the MAIN CONTROL BOARD.
C1
Residual Flame
Gas valve leakage.
Replace the gas valve.
C4
Vent Blockage
Vent pipe blockage.
Ambient wind pressure
too high.
Air pressure sensor failure.
Fan failure.
Clean & remove debris from the vent pipe.
Change the terminal to resist higher
wind pressure.
Replace air pressure sensor module.
Replace the fan.
C9
Exhaust Gas
Temperature
Sensor Failure
Exhaust gas temperature
sensor is open or has
short-circuited.
• Ensure the sensor is connected
• If the sensor is connected & C9 persists,
change the sensor.
• If C9 persists with a new sensor, change
the MAIN CONTROL BOARD .
• Ensure the sensor is connected
• If the sensor is connected & CF persists,
change the sensor.
• If CF persists with a new sensor, change
the MAIN CONTROL BOARD .
CA
Exhaust Gas
Temperature
Too High
Heat exchanger failure.
Exhaust gas temperature
failure.
Change the heat exchanger.
Refer to C9 above.
CB
Bypass Water
Valve Failure
Bypass water valve jam.
Bypass water valve failure.
Clean the bypass water valve.
Replace the bypass water valve.
CF
Heat Exchanger
Outlet Temperature
Sensor Failure
Heat exchanger outlet
temperature sensor is open
or has short-circuited.
Main water valve failure.
Replace the main water valve.
Close & open the faucet to restart
combustion operation.
** These error codes will not display on the screen, but can be accessed in the after-sales mode.
WARNING
This water heater is equipped with a blocked vent shut-off system. Should error codes E5 or C4
occur, turn off the gas valve at the manual shut-off point. Then, check the vent terminations for
obstructions. If none are found, press the power button to reset the water heater. If the error
code persists, call a qualified service technician or the gas supplier to check the water heater.
Failure to follow these instructions could result in property damage, personal injury or death.
