Noritz
Noritz Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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11
Boiler will not ignite; display shows error 11 shortly after a call for heat or hot water.
Ignition Failure
12
Boiler ignites briefly then shuts down; display shows error 12 and burner goes out.
Flame Loss During Operation
14
Boiler shuts down and displays error 14 after running for a short period.
Thermal Fuse or Overheat Cutoff Activation
16
Boiler runs then shuts down with error 16; unit feels very hot to the touch.
Outlet Water Overheat
20
Boiler stops and shows error 20; may occur intermittently during operation.
High Limit Switch Activation
29
Boiler displays error 29 and may shut down shortly after starting.
Condensate Drain or Neutralizer Fault
31
Boiler will not start and shows error 31 on the display.
Inlet Thermistor Failure
32
Boiler displays error 32 and will not operate.
Outlet Thermistor Failure
33
Boiler shows error 33 and stops heating.
Heat Exchanger Thermistor Failure
34
Boiler displays error 34 and will not fire.
Combustion Air Temperature Sensor Fault
51
Boiler shows error 51 and does not respond to thermostat or controller commands.
Gas Modulation Valve Control Fault
52
Boiler displays error 52 and will not ignite.
Gas Modulation Valve Signal Error
61
Boiler shows error 61 and the combustion fan does not start or runs erratically.
Combustion Fan Motor Failure
65
Boiler displays error 65 and may shut down during operation.
Water Flow Control Fault
70
Boiler shows error 70 and is completely inoperative.
Main Control Board Failure
71
Boiler displays error 71 and will not operate.
Gas Valve Circuit Failure
72
Boiler shows error 72 and may attempt to start but fails.
Flame Rod Signal Abnormality
73
Boiler displays error 73 and does not respond to user inputs.
Internal Control Board Configuration Error
90
Boiler shows error 90 and shuts down during operation.
Abnormal Combustion
91
Boiler displays error 91 and may not maintain stable operation.
Combustion Fan Feedback Error
92
Boiler shows error 92 and fails to modulate correctly.
Fan Speed Control Error
93
Boiler displays error 93 and may lock out.
Gas Valve Feedback Error
94
Boiler shows error 94 and shuts down during operation.
Flame Detection Abnormality During Combustion
99
Boiler displays error 99 and locks out; may be accompanied by strong exhaust smell.
Flame Detection Failure at Ignition
Symptom
Boiler cabinet is excessively hot to the touch during operation.
Inadequate Cooling / Internal Overheating
Symptom
Boiler display shows fluctuating temperatures and heating is unstable, but no error code is present.
Sensor Drift / Intermittent Thermistor Fault
Symptom
Boiler does not power on at all; display is blank and no lights or sounds are present.
No Power / Power Supply Failure
Symptom
Boiler emits a high-pitched whine or loud humming during operation.
Combustion Fan or Pump Noise
Symptom
Boiler frequently cycles on and off in short intervals during heating demand.
Short Cycling
Symptom
Boiler frequently loses pressure and requires regular topping up of system water.
Chronic System Pressure Loss
Symptom
Boiler is very noisy with gurgling sounds in pipes and radiators.
Air Entrapment in Heating System
Symptom
Boiler locks out intermittently during very cold weather without a specific error code.
Freeze Protection / Low Temperature Lockout
Symptom
Boiler or nearby piping makes loud banging or knocking noises when starting or stopping.
Water Hammer / Thermal Expansion Noise
Symptom
Boiler pressure rises excessively during heating and may trigger the relief valve.
Over-Pressurization
Symptom
Boiler runs but does not provide enough heat to the radiators or underfloor system.
Insufficient Heating Output
Symptom
Boiler shuts down when multiple heating zones call at once, but runs with a single zone.
Flow / Load Imbalance
Symptom
Boiler's condensate drain repeatedly clogs, causing water to back up inside the unit.
Recurring Condensate Blockage
Symptom
Boiler's display and controls work, but there is no call for heat from the thermostat.
Control Signal / Thermostat Interface Issue
Symptom
Strong exhaust or burning smell near the boiler during operation.
Flue Gas Leakage / Venting Problem
Symptom
Water is leaking from the bottom of the Noritz boiler cabinet.
Internal Water Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 11 |
Boiler will not ignite; display shows error 11 shortly after a call for heat or hot water.
|
Ignition Failure | View Details |
| 12 |
Boiler ignites briefly then shuts down; display shows error 12 and burner goes out.
|
Flame Loss During Operation | View Details |
| 14 |
Boiler shuts down and displays error 14 after running for a short period.
|
Thermal Fuse or Overheat Cutoff Activation | View Details |
| 16 |
Boiler runs then shuts down with error 16; unit feels very hot to the touch.
|
Outlet Water Overheat | View Details |
| 20 |
Boiler stops and shows error 20; may occur intermittently during operation.
|
High Limit Switch Activation | View Details |
| 29 |
Boiler displays error 29 and may shut down shortly after starting.
|
Condensate Drain or Neutralizer Fault | View Details |
| 31 |
Boiler will not start and shows error 31 on the display.
|
Inlet Thermistor Failure | View Details |
| 32 |
Boiler displays error 32 and will not operate.
|
Outlet Thermistor Failure | View Details |
| 33 |
Boiler shows error 33 and stops heating.
|
Heat Exchanger Thermistor Failure | View Details |
| 34 |
Boiler displays error 34 and will not fire.
|
Combustion Air Temperature Sensor Fault | View Details |
| 51 |
Boiler shows error 51 and does not respond to thermostat or controller commands.
|
Gas Modulation Valve Control Fault | View Details |
| 52 |
Boiler displays error 52 and will not ignite.
|
Gas Modulation Valve Signal Error | View Details |
| 61 |
Boiler shows error 61 and the combustion fan does not start or runs erratically.
|
Combustion Fan Motor Failure | View Details |
| 65 |
Boiler displays error 65 and may shut down during operation.
|
Water Flow Control Fault | View Details |
| 70 |
Boiler shows error 70 and is completely inoperative.
|
Main Control Board Failure | View Details |
| 71 |
Boiler displays error 71 and will not operate.
|
Gas Valve Circuit Failure | View Details |
| 72 |
Boiler shows error 72 and may attempt to start but fails.
|
Flame Rod Signal Abnormality | View Details |
| 73 |
Boiler displays error 73 and does not respond to user inputs.
|
Internal Control Board Configuration Error | View Details |
| 90 |
Boiler shows error 90 and shuts down during operation.
|
Abnormal Combustion | View Details |
| 91 |
Boiler displays error 91 and may not maintain stable operation.
|
Combustion Fan Feedback Error | View Details |
| 92 |
Boiler shows error 92 and fails to modulate correctly.
|
Fan Speed Control Error | View Details |
| 93 |
Boiler displays error 93 and may lock out.
|
Gas Valve Feedback Error | View Details |
| 94 |
Boiler shows error 94 and shuts down during operation.
|
Flame Detection Abnormality During Combustion | View Details |
| 99 |
Boiler displays error 99 and locks out; may be accompanied by strong exhaust smell.
|
Flame Detection Failure at Ignition | View Details |
| – |
Boiler cabinet is excessively hot to the touch during operation.
|
Inadequate Cooling / Internal Overheating | View Details |
| – |
Boiler display shows fluctuating temperatures and heating is unstable, but no error code is present.
|
Sensor Drift / Intermittent Thermistor Fault | View Details |
| – |
Boiler does not power on at all; display is blank and no lights or sounds are present.
|
No Power / Power Supply Failure | View Details |
| – |
Boiler emits a high-pitched whine or loud humming during operation.
|
Combustion Fan or Pump Noise | View Details |
| – |
Boiler frequently cycles on and off in short intervals during heating demand.
|
Short Cycling | View Details |
| – |
Boiler frequently loses pressure and requires regular topping up of system water.
|
Chronic System Pressure Loss | View Details |
| – |
Boiler is very noisy with gurgling sounds in pipes and radiators.
|
Air Entrapment in Heating System | View Details |
| – |
Boiler locks out intermittently during very cold weather without a specific error code.
|
Freeze Protection / Low Temperature Lockout | View Details |
| – |
Boiler or nearby piping makes loud banging or knocking noises when starting or stopping.
|
Water Hammer / Thermal Expansion Noise | View Details |
| – |
Boiler pressure rises excessively during heating and may trigger the relief valve.
|
Over-Pressurization | View Details |
| – |
Boiler runs but does not provide enough heat to the radiators or underfloor system.
|
Insufficient Heating Output | View Details |
| – |
Boiler shuts down when multiple heating zones call at once, but runs with a single zone.
|
Flow / Load Imbalance | View Details |
| – |
Boiler's condensate drain repeatedly clogs, causing water to back up inside the unit.
|
Recurring Condensate Blockage | View Details |
| – |
Boiler's display and controls work, but there is no call for heat from the thermostat.
|
Control Signal / Thermostat Interface Issue | View Details |
| – |
Strong exhaust or burning smell near the boiler during operation.
|
Flue Gas Leakage / Venting Problem | View Details |
| – |
Water is leaking from the bottom of the Noritz boiler cabinet.
|
Internal Water Leak | View Details |
No matching codes found
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