Noritz Error Codes and
Troubleshooting guide
(updated 2017)


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Understanding Noritz error codes and the troubleshooting Noritz water heaters. Find out what the most common problems in Noritz water heaters are, about the symptoms and fixing tips.

Every Noritz tankless water heater, either outdoor or indoor model, can be connected to remote controller, and when the problems occurs, it displays the error codes on its screen, which helps users and technicians to fix the problem.

The error codes are represented by the two-digit numbers, such as the 10, 11.... 99 and the display and operation light will flash together when the failure occurs. The following text gives the information about the most common problems and its error codes displayed on the remote controller.

It will be assumed that the water heater is properly installed, with the correct gas type, and per codes. The tools needed to solve the problems from below are mainly the screwdriver, manometer and voltmeter.

Noritz tankless water heaters have many advanced features and elements that are connected and controlled by the electronic board, so it is required to have a knowledge and skills for the successful repair.

So before calling a technician, which are usually expensive to hire, or if hesitating to deal with the problem, try to get some free quotes from networx.com, and plumbers from your area, with no obligation, and then decide.

Noritz error codes list

Error Code 05

Problem: Service warning.

Solution: This is not an error code but is the automatic service reminder that informs you that it is time to call the Noritz licensed technician. Do not reset the water heater error code before the service; otherwise the unit might fail prematurely.

Error Code 10

Problem: The error code 10 shows the problem in gas combustion that causes the power level drop, while the combustion continues even after shutdown.

Solution: Check for foreign materials found on the burner which is burning after gas combustion stops. To reset the error code 10, the power must be disconnected. If there is a recirculation loop use an aquastat to keep 10 degree differential.

Error Code 11

Problem: The ignition fails.

Solution: Make sure that the gas pressure has a correct value and per manufacturers specs., that there are no obstructions in venting and flame rod is clean, together with the ignition plug.

Error Code 12

Problem: Burner flame loss during operation; flame rod does not detect flame.

Solution: Check for the incoming gas pressure. Remove any obstructions in the venting system. Clean the ignition plug and flame rod.

Error Code 14

Problem: Thermal fuse failure.

Solution: Replace the thermal fuse if you see the error code 14. Make sure that the water heater has no restriction in air flow and the gas burns properly. Also, check the water quality as the poor quality may affect the heat exchanger function, and lead to the element replacement, unless flushed on time.

Error Code 16

Problem: Extremely high water temperature.

Solution: Your Noritz water heater might need descaling due to the sediment and lime scale build up. Manifold pressure might need an adjustment.

Error Code 20

Problem: Activation of the high limit switch.

Solution: Check is the high limit switch working properly. Remove the limescale that causes the high temperature of hot water.

Error Code 29

Problem: High water level in the neutralizer and clogging.

Solution: Make sure the draining is proper so there is no clogging of condensate drain pipe. Water level sensor on the neutralizer must be free of moisture so the pipe will not freeze.

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Error Code 31

Problem: Problem with the inlet thermistor.

Solution: Replace the inlet thermistor.

Error Code 32

Problem: Problem with the outlet thermistor.

Solution: Replace the outlet thermistor.

Error Code 33

Problem: Heat exchanger thermistor malfunction.

Solution: Replace the thermistor.

Error Code 59

Problem: Low input BTU, problems with the combustion.

Solution: The gas combustion chamber does not get enough fresh air or the products of combustion are not vented fully because of the blockage in vents. Remove any blockage in venting. Clean the fan motor and burner chamber. Also, the water heater should be adjust for the right height elevation.

Error Code 61

Problem: Faulty fan motor.

Solution: Measure the incoming voltage. Check and replace if needed the fan motor or circuit board.

Error Code 66

Problem: Problem with the bypass flow control valve.

Solution: If there is a blockage of bypass servo, correct it. If the element is not operating properly, replace it.

Error Code 70

Problem: Faulty circuit board.

Solution: Replace the circuit board.

Error Code 71

Problem: Gas valve drive circuit abnormality.

Solution: The error code 71 happens if the water heater is connected to the battery backup, solar power or generator and if there is a fluctuation in voltage supply. Check the voltage from the circuit board due to the damage.

Error Code 72

Problem: The flame rod detects the flame without the ignition sequence.

Solution: The unit must have proper grounding. Check if there is damage on the circuit board and flame detection circuit.

Error Code 73

Problem: The problem with the circuit board setting.

Solution: Reset the heater by disconnecting the power and check the circuit board programming.

Error Code F76

Problem: The communication error for the multi-system.

Solution: Disconnect the power to reset the unit and make sure the connect cord is not damaged.

Error Code 760

Problem: Problems with the remote controller.

Solution: Reset the unit, check the wire connections and make sure that only one controller is connected.

Error Codes 90 and 99

Problem: Gas combustion problem.

Solution: Make sure the flame color is light blue (yellow tips are allowed). Remove any blockage in flue vent.

Error Codes 92 and 93

Problem: Neutralizer life cycle alert.

Solution: Neutralizer must be replaced if its lifecycle is about to end; also you must reset the burner timer.

If you see that fixing your Noritz water heater is hard, takes too much time and money, check out with the professional technicians then, but first get some free quotes from your local plumber (if applicable) to know what to expect. 

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