Error Code	Symptom	Fault Type	Guide
E0	Digital Reliance water heater display shows E0 and unit will not heat water	Control Board Communication Fault	View Details
E1	Reliance tankless or hybrid water heater shows E1 and shuts down, no hot water	Water Flow Sensor / Low Flow Fault	View Details
E10	Reliance water heater shows E10 and shuts down, often accompanied by gurgling or boiling sounds	Dry-Fire / No Water in Heat Exchanger or Tank	View Details
E2	Reliance water heater displays E2 and burner or elements will not operate	Outlet Temperature Sensor (Thermistor) Fault	View Details
E3	Reliance tankless or power vent water heater shows E3 and shuts down during operation	Exhaust / Flue Temperature Overheat	View Details
E4	Reliance water heater shows E4 and will not ignite or heat	Inlet Temperature Sensor (Thermistor) Fault	View Details
E5	Reliance tankless or hybrid water heater displays E5 and shuts down shortly after starting	Overheat / High Limit Thermostat Trip	View Details
E6	Reliance water heater shows E6 and does not heat properly	Tank / Internal Temperature Sensor Fault	View Details
E7	Reliance tankless water heater displays E7 and will not ignite	Ignition Failure / Flame Not Detected	View Details
E8	Reliance water heater shows E8 and shuts down during operation	Fan / Blower Motor Fault	View Details
E9	Reliance water heater displays E9 and will not operate	Gas Valve / Gas Control Fault	View Details
F1	Reliance hybrid/heat pump water heater shows F1 and runs only in backup electric mode or not at all	Heat Pump Compressor Fault	View Details
F2	Reliance hybrid water heater displays F2 and heat pump mode is disabled	Evaporator Coil Temperature Sensor Fault	View Details
F3	Reliance hybrid water heater shows F3 and may shut down heat pump operation	Condenser Coil Temperature Sensor Fault	View Details
F4	Reliance hybrid water heater displays F4 and fan may not run	Heat Pump Fan Motor Fault	View Details
F5	Reliance hybrid water heater shows F5 and may stop heating in heat pump mode	Ambient Air Temperature Sensor Fault	View Details
F6	Reliance hybrid water heater displays F6 and may revert to electric-only mode	Refrigerant System Protection / High or Low Pressure Fault	View Details
F7	Reliance hybrid water heater shows F7 and may not respond to control inputs	User Interface / Display Board Fault	View Details
F8	Reliance hybrid water heater displays F8 and may not heat efficiently	Tank Temperature Sensor Disagreement / Calibration Fault	View Details
F9	Reliance hybrid water heater shows F9 and may lock out heating	Leak Detection / Condensate Overflow Fault (if equipped)	View Details
None	Pilot light will not stay lit on Reliance atmospheric gas water heater	Thermocouple / Flame Sensor Failure	View Details
–	Condensation or water pooling on top of or around Reliance water heater shortly after installation	Normal Condensation or Minor Fitting Leaks	View Details
–	No hot water from Reliance electric water heater (both elements off, no error code)	Tripped High-Limit Reset or Failed Upper Thermostat	View Details
–	Reliance electric water heater has some hot water but runs out quickly	Failed Lower Heating Element or Lower Thermostat	View Details
–	Reliance gas water heater burner will not light, but pilot stays lit	Faulty Gas Control Valve or Clogged Main Burner Orifice	View Details
–	Reliance hybrid water heater runs fan/compressor constantly but water is not getting hot enough	Insufficient Heat Pump Capacity or Sensor Misreading	View Details
–	Reliance power vent water heater fan runs but burner does not ignite	Pressure Switch or Air Proving Switch Fault	View Details
–	Reliance tankless water heater cycles on and off rapidly (temperature swings at fixtures)	Short Cycling Due to Flow or Gas Issues	View Details
–	Reliance water heater leaking from bottom or around drain valve	Leaking Drain Valve or Tank Failure	View Details
–	Reliance water heater leaking from top around hot or cold connections	Leaking Dielectric Nipples or Loose Pipe Connections	View Details
–	Reliance water heater makes loud banging or hammering noises when water is turned on or off	Water Hammer / Plumbing Shock	View Details
–	Reliance water heater makes popping or rumbling noises during heating	Sediment Buildup on Tank Bottom or Heat Exchanger	View Details
–	Reliance water heater outer jacket feels excessively hot to the touch	Insulation Degradation or Overheating	View Details
–	Reliance water heater produces rotten egg or sulfur smell in hot water	Anaerobic Bacteria Reaction with Magnesium Anode Rod	View Details
–	Reliance water heater trips the electrical breaker repeatedly	Electrical Short or Overcurrent in Heater Circuit	View Details
–	Rust-colored or discolored hot water from Reliance water heater	Corroded Anode Rod or Tank Interior Corrosion	View Details
–	Temperature and pressure (T&P) relief valve on Reliance water heater is dripping or discharging water	Excessive Pressure or Temperature / Faulty T&P Valve	View Details
–	Water is too hot from Reliance water heater (scalding at taps)	Thermostat Stuck Closed or Set Too High	View Details

Reliance Water Heaters Error Codes

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