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ErrBase

Rinnai Waterheater Error Codes

All Rinnai waterheater error codes with step-by-step troubleshooting, multimeter specs, and OEM part numbers.

16 error codes

CodeMeaning
10The unit detected that no gas was available or the gas valve was unable to open when a heating demand was made.
highbeginner
11The unit attempted to ignite 3 times and no flame was detected by the flame rod. The burner has locked out as a safety measure.
highintermediate
12The burner successfully ignited but the flame extinguished unexpectedly during a heating cycle. The unit shut down to prevent unsafe operation.
highintermediate
14The one-time thermal fuse (thermal cutoff) protecting the heat exchanger has blown, indicating the exchanger reached a dangerously high temperature. The unit is locked out until the fuse is replaced.
criticaladvanced
15The burner has been locked out following an abnormal combustion sequence during ignition. The unit detected an irregularity during the ignition attempt and shut down as a safety measure.
highintermediate
17The gas valve was unable to modulate or operate correctly as commanded by the control board. An abnormal voltage or position was detected during the heating cycle.
highadvanced
25The bath fill sequence did not complete within the programmed time limit. This code only appears on Rinnai models equipped with the built-in bath fill or ThermaCirc recirculation feature.
lowbeginner
32The outlet NTC sensor caught the water temp climbing past the safe limit and triggered a safety shutdown. It's protecting the heat exchanger from warping and preventing the thermal fuse from blowing, which would be a much worse and more expensive problem.
highintermediate
52The modulating gas valve couldn't reach or hold the target firing position commanded by the PCB. Basically the valve's modulation mechanism failed to operate correctly, so the unit can't control flame height.
highadvanced
55The unit detected combustion that's outside normal operating parameters. Could be incomplete combustion, instability in the flame, or an air-to-fuel ratio the sensors flagged as wrong. Basically the machine knows something's off with how it's burning and it's shutting itself down to keep you safe.
highintermediate
61The combustion fan motor has failed to start or stopped operating completely. The unit cannot initiate or sustain a heating cycle without a functioning blower.
highadvanced
63The combustion fan (blower) did not reach the required speed within the expected time, or the fan speed sensor reported an abnormal reading during startup or operation.
highintermediate
79The sensor measuring the temperature of combustion air entering the unit has failed or is reading outside its expected range.
moderateintermediate
HUBThis is the reference hub for all Rinnai RU and V series error codes. When the unit detects a fault, it throws a two-digit number on the controller display and shuts down to protect itself. Each number maps to a specific sensor or system that's either failing or reading outside its normal range.
lowbeginner
NO-HOT-WATERThe unit's control board triggered a safety shutdown because it detected a failure in ignition, flow, or venting. The burner assembly isn't firing, or it fires and cuts out immediately. That controller is reading sensor data in real time and killing the gas valve the moment something falls outside acceptable parameters.
moderateintermediate
RESETStep-by-step instructions for performing soft, hard, and factory resets on Rinnai tankless water heaters to clear error codes and restore normal operation.
lowbeginner