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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 water temperature sensor detected that the water leaving the heat exchanger exceeded the maximum safe limit. The unit shut down to prevent scalding or heat exchanger damage.
highintermediate
52The modulating gas valve was unable to reach or hold the target firing position commanded by the PCB. The valve's modulation mechanism has failed to operate correctly.
highadvanced
55The unit detected combustion that is outside normal operating parameters. This can mean incomplete combustion, combustion instability, or an air-to-fuel ratio that the sensors have flagged as abnormal.
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
HUBReference hub covering all Rinnai RU and V series tankless water heater error codes with diagnosis and repair guidance.
lowbeginner
NO-HOT-WATERError Code, Flow, and Flame Fixes
mediumintermediate
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