CTC
CTC Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
Water heater powers on but display shows E0 and unit will not start heating
Control Panel Communication Fault
E1
Display shows E1 and burner or heating elements do not activate
Inlet Thermistor / Temperature Sensor Fault
E10
Display shows E10, and the unit does not start; the fan may run briefly (gas models).
Exhaust Fan / Combustion Blower Fault
E11
Display shows E11, and the burner shuts off shortly after ignition (gas models).
Flame Loss / Flame Signal Weak
E12
Display shows E12, and the unit will not ignite; the fan may run continuously (gas models).
Air Pressure Switch / Draft Proving Fault
E13
Display shows E13, and the unit locks out; this may occur after long operation.
Exhaust Over-Temperature / Flue Sensor Fault
E14
Display shows E14, and the unit will not start; there is no fan or ignition (gas models).
Gas Valve Drive Circuit Fault
E15
Display shows E15, and the unit intermittently shuts down or resets.
Low Voltage / Power Supply Fault
E16
Display shows E16, and the unit will not heat; elements do not energize (electric models).
Heating Element Circuit Fault
E17
Display shows E17, and the unit cycles off due to high temperature; the tank feels extremely hot (electric models).
Tank Thermostat/Sensor Fault
E18
Display shows E18, and the unit does not respond to buttons or remote control.
User Interface Keypad Fault
E19
Display shows E19, and the unit locks out after several failed start attempts.
Lockout Due to Repeated Faults
E2
Display shows E2 and water temperature is unstable or unit shuts down shortly after starting
Outlet Thermistor / Temperature Sensor Fault
E20
Display shows E20, and the unit will not start; often after a leak or condensation event.
Condensate/Leak Detection Fault
E3
Display shows E3 and unit shuts down shortly after ignition or element activation
Overheat / High Limit Thermostat Trip
E4
Display shows E4 and burner will not ignite (gas models only)
Ignition Failure / Flame Not Detected
E5
Display shows E5 and unit shuts down during operation, often with very hot outlet water
Outlet Over-Temperature Protection
E6
Display shows E6, and the unit cycles on and off rapidly or fails to maintain the set temperature.
Flow Sensor / Turbine Fault
E7
Display shows E7, and the unit does not respond to temperature adjustments.
Outlet Temperature Sensor Calibration Error
E8
Display shows E8, and the unit shuts down, often accompanied by rumbling or boiling sounds.
Heat Exchanger Overheat (Tankless) / Dry-Fire Protection (Electric)
E9
Display shows E9, and the unit will not operate; this may occur after a power surge.
EEPROM / Control Memory Error
Symptom
CTC gas water heater has a yellow or sooty flame.
Improper Combustion / Incomplete Burning
Symptom
CTC gas water heater pilot will not stay lit (standing pilot models).
Thermocouple / Flame Sensor Failure
Symptom
CTC tankless water heater cycles between hot and cold water during a shower
Temperature Fluctuation / Short Cycling
Symptom
CTC water heater T&P (temperature and pressure) relief valve is dripping or discharging water.
Excessive Pressure / Temperature or Faulty T&P Valve
Symptom
CTC water heater causes banging or knocking in pipes when turning on or off.
Water Hammer / Thermal Expansion Noise
Symptom
CTC water heater condensate is leaking from joints or onto the floor (condensing gas models)
Condensate Drainage Problem
Symptom
CTC water heater display works but buttons are unresponsive or intermittent
Keypad / Interface Failure
Symptom
CTC water heater does not power on; the display is blank.
No Power / Control Not Energized
Symptom
CTC water heater emits a high-pitched whistling or hissing sound when running.
Restricted Flow / Pressure Imbalance
Symptom
CTC water heater fan runs continuously even when no hot water is being used (gas models)
Stuck Fan Relay / Post-Purge Malfunction
Symptom
CTC water heater leaks from the top, around piping connections.
Top Fitting / Connection Leak
Symptom
CTC water heater makes popping or rumbling noises during heating.
Sediment Boiling / Scale Buildup
Symptom
CTC water heater produces a rotten egg or sulfur smell in hot water.
Bacterial Contamination / Anode Reaction
Symptom
CTC water heater trips the circuit breaker or blows fuses.
Electrical Short / Overcurrent
Symptom
Hot water runs out quickly; the CTC tank-type water heater recovers very slowly.
Reduced Hot Water Capacity
Symptom
No hot water at all; the CTC water heater appears powered, but the water remains cold.
Complete Heating Failure
Symptom
The CTC water heater leaks from the bottom of the unit.
Tank or Heat Exchanger Leak
Symptom
Water is too hot; there is a risk of scalding from the CTC water heater.
Overheating/Thermostat Out of Calibration
Symptom
Water is warm but not hot enough, even when the CTC water heater is set to a high temperature.
Insufficient Heating/Under-Temperature
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Water heater powers on but display shows E0 and unit will not start heating
|
Control Panel Communication Fault | View Details |
| E1 |
Display shows E1 and burner or heating elements do not activate
|
Inlet Thermistor / Temperature Sensor Fault | View Details |
| E10 |
Display shows E10, and the unit does not start; the fan may run briefly (gas models).
|
Exhaust Fan / Combustion Blower Fault | View Details |
| E11 |
Display shows E11, and the burner shuts off shortly after ignition (gas models).
|
Flame Loss / Flame Signal Weak | View Details |
| E12 |
Display shows E12, and the unit will not ignite; the fan may run continuously (gas models).
|
Air Pressure Switch / Draft Proving Fault | View Details |
| E13 |
Display shows E13, and the unit locks out; this may occur after long operation.
|
Exhaust Over-Temperature / Flue Sensor Fault | View Details |
| E14 |
Display shows E14, and the unit will not start; there is no fan or ignition (gas models).
|
Gas Valve Drive Circuit Fault | View Details |
| E15 |
Display shows E15, and the unit intermittently shuts down or resets.
|
Low Voltage / Power Supply Fault | View Details |
| E16 |
Display shows E16, and the unit will not heat; elements do not energize (electric models).
|
Heating Element Circuit Fault | View Details |
| E17 |
Display shows E17, and the unit cycles off due to high temperature; the tank feels extremely hot (electric models).
|
Tank Thermostat/Sensor Fault | View Details |
| E18 |
Display shows E18, and the unit does not respond to buttons or remote control.
|
User Interface Keypad Fault | View Details |
| E19 |
Display shows E19, and the unit locks out after several failed start attempts.
|
Lockout Due to Repeated Faults | View Details |
| E2 |
Display shows E2 and water temperature is unstable or unit shuts down shortly after starting
|
Outlet Thermistor / Temperature Sensor Fault | View Details |
| E20 |
Display shows E20, and the unit will not start; often after a leak or condensation event.
|
Condensate/Leak Detection Fault | View Details |
| E3 |
Display shows E3 and unit shuts down shortly after ignition or element activation
|
Overheat / High Limit Thermostat Trip | View Details |
| E4 |
Display shows E4 and burner will not ignite (gas models only)
|
Ignition Failure / Flame Not Detected | View Details |
| E5 |
Display shows E5 and unit shuts down during operation, often with very hot outlet water
|
Outlet Over-Temperature Protection | View Details |
| E6 |
Display shows E6, and the unit cycles on and off rapidly or fails to maintain the set temperature.
|
Flow Sensor / Turbine Fault | View Details |
| E7 |
Display shows E7, and the unit does not respond to temperature adjustments.
|
Outlet Temperature Sensor Calibration Error | View Details |
| E8 |
Display shows E8, and the unit shuts down, often accompanied by rumbling or boiling sounds.
|
Heat Exchanger Overheat (Tankless) / Dry-Fire Protection (Electric) | View Details |
| E9 |
Display shows E9, and the unit will not operate; this may occur after a power surge.
|
EEPROM / Control Memory Error | View Details |
| – |
CTC gas water heater has a yellow or sooty flame.
|
Improper Combustion / Incomplete Burning | View Details |
| – |
CTC gas water heater pilot will not stay lit (standing pilot models).
|
Thermocouple / Flame Sensor Failure | View Details |
| – |
CTC tankless water heater cycles between hot and cold water during a shower
|
Temperature Fluctuation / Short Cycling | View Details |
| – |
CTC water heater T&P (temperature and pressure) relief valve is dripping or discharging water.
|
Excessive Pressure / Temperature or Faulty T&P Valve | View Details |
| – |
CTC water heater causes banging or knocking in pipes when turning on or off.
|
Water Hammer / Thermal Expansion Noise | View Details |
| – |
CTC water heater condensate is leaking from joints or onto the floor (condensing gas models)
|
Condensate Drainage Problem | View Details |
| – |
CTC water heater display works but buttons are unresponsive or intermittent
|
Keypad / Interface Failure | View Details |
| – |
CTC water heater does not power on; the display is blank.
|
No Power / Control Not Energized | View Details |
| – |
CTC water heater emits a high-pitched whistling or hissing sound when running.
|
Restricted Flow / Pressure Imbalance | View Details |
| – |
CTC water heater fan runs continuously even when no hot water is being used (gas models)
|
Stuck Fan Relay / Post-Purge Malfunction | View Details |
| – |
CTC water heater leaks from the top, around piping connections.
|
Top Fitting / Connection Leak | View Details |
| – |
CTC water heater makes popping or rumbling noises during heating.
|
Sediment Boiling / Scale Buildup | View Details |
| – |
CTC water heater produces a rotten egg or sulfur smell in hot water.
|
Bacterial Contamination / Anode Reaction | View Details |
| – |
CTC water heater trips the circuit breaker or blows fuses.
|
Electrical Short / Overcurrent | View Details |
| – |
Hot water runs out quickly; the CTC tank-type water heater recovers very slowly.
|
Reduced Hot Water Capacity | View Details |
| – |
No hot water at all; the CTC water heater appears powered, but the water remains cold.
|
Complete Heating Failure | View Details |
| – |
The CTC water heater leaks from the bottom of the unit.
|
Tank or Heat Exchanger Leak | View Details |
| – |
Water is too hot; there is a risk of scalding from the CTC water heater.
|
Overheating/Thermostat Out of Calibration | View Details |
| – |
Water is warm but not hot enough, even when the CTC water heater is set to a high temperature.
|
Insufficient Heating/Under-Temperature | View Details |
No matching codes found
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