Rinnai
SENSEI® RX Series featuring the RXP Model with Built-in Pump and Smart-Circ™ Intelligent Recirculation features set these models out from the crowd.
Rinnai RE199eN 199,000 BTU Outdoor Non-Condensing Natural Gas Tankless Water Heater
 Rinnai High Efficiency Non-Condensing 8.5 GPM Residential 180,000 BTU Interior Natural Gas Tankless Water Heater
Top 10 Tankless Water Heater Error Codes & How to Fix Them
These are the most common fault categories homeowners and plumbers encounter across major brands like Navien, Rinnai, Rheem, Noritz, Takagi, and A.O. Smith. Exact code numbers vary by manufacturer, but the causes are very similar.
Common Error What It Means How to Fix It
Flame Failure
Flame starts but won't stay lit.
Clean the flame rod, inspect the burner, and have gas pressure checked.
Venting / Exhaust Error
Blocked or restricted exhaust.
Remove obstructions, inspect intake/exhaust pipes, and verify proper vent installation.
4
Overheat Error
Water temperature exceeded the safety limit.
Clean the inlet filter, descale the heat exchanger, and verify adequate water flow.
5
Low Water Flow
Insufficient flow to activate the heater.
Clean faucet aerators and inlet filters, verify valves are fully open, and check incoming water pressure.
7
Thermistor / Temperature Sensor Fault
Temperature sensor isn't reading correctly.
Inspect wiring, check sensor resistance, and replace the sensor if faulty.
8
Check for debris, inspect electrical connections, and replace the fan if necessary.
9
Verify gas pressure with proper test equipment and inspect the gas valve.
10