Rheem Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E0
Boiler display shows E0 and unit will not fire
Communication Fault Between Main PCB and User Interface
E1
Boiler shows E1 and will not ignite, fan may start then stop
Ignition Failure / No Flame Detected
E10
Boiler displays E10 and will not start, often after sensor wiring work
Flow Temperature Sensor Fault (Open or Shorted)
E11
Boiler shows E11 and may cycle erratically, temperature readings appear incorrect
Return Temperature Sensor Fault
E12
Boiler displays E12 and may not respond to thermostat calls correctly
Outdoor Temperature Sensor Fault (Weather Compensation Systems)
E13
Boiler shows E13 and may shut down during domestic hot water demand
Domestic Hot Water (DHW) Temperature Sensor Fault
E14
Boiler displays E14 and may not modulate correctly, fan speed appears erratic
Fan Speed Feedback / Tachometer Fault
E15
Boiler shows E15 and may not respond to thermostat or zone calls
External Control / Thermostat Input Fault
E16
Boiler displays E16 and may shut down when switching between heating and DHW
Diverter Valve / 3-Way Valve Position Fault (Combi Boilers)
E17
Boiler shows E17 and may not fire even though there is a call for heat
Flow Switch / Flow Sensor Fault (Combi DHW or System Flow)
E18
Boiler displays E18 and may show incorrect system pressure or lock out on pressure error
System Pressure Sensor Fault
E19
Boiler shows E19 and may not start, often after a power surge or lightning event
Internal Memory / Parameter Corruption
E2
Boiler displays E2 and shuts down shortly after starting
Flame Loss During Operation
E3
Boiler shows E3 and will not start, fan may run briefly
Exhaust / Flue Temperature Overheat
E4
Boiler displays E4 and shuts down, often after running for a short period
Water Outlet Temperature Overheat / High Limit Trip
E5
Boiler shows E5 and will not fire, often accompanied by low or zero system pressure
Low Water Pressure / Low Water Sensor Fault
E6
Boiler displays E6 and shuts down, often with noisy boiling sounds inside the unit
Overheat Thermostat Trip / Manual Reset High Limit
E7
Boiler shows E7 and will not start, fan may not run
Fan / Combustion Blower Fault
E8
Boiler displays E8 and locks out, often after several failed ignition attempts
Gas Valve / Gas Supply Fault
E9
Boiler shows E9 and will not operate, often after a power event or wiring change
Polarity / Grounding / Line Voltage Error
EA
Boiler displays EA and locks out, often with fan running but no ignition
Air Pressure Switch / Draft Proving Fault
EC
Boiler shows EC and shuts down, often during long heating cycles
Condensate Drain / Trap Fault
Symptom
Boiler display is on but there is no response to thermostat calls (no flame icon, no fan)
Control Lockout or No Call for Heat Recognition
Symptom
Boiler display shows normal operation but there is no domestic hot water flow when a tap is opened (combi models)
No DHW Flow Detection
Symptom
Boiler does not start at all, display is blank
No Power / Dead Boiler
Symptom
Boiler emits a burning smell or plastic odor during operation
Overheating Electrical or Plastic Components
Symptom
Boiler frequently loses pressure over days or weeks without visible leaks
Hidden System Leak or Expansion Tank Issue
Symptom
Boiler frequently trips the household circuit breaker or blows fuses
Electrical Short or Overload in Boiler
Symptom
Boiler ignites but shuts down after a few seconds, with no specific error code displayed
Marginal Flame Detection / Weak Flame Signal
Symptom
Boiler is excessively noisy (vibration, humming, or rattling)
Mechanical Vibration / Loose Components
Symptom
Boiler leaking from pressure relief valve discharge pipe
Overpressure / Expansion System Failure
Symptom
Boiler leaking water from bottom of cabinet
Internal Water Leak
Symptom
Boiler locks out intermittently during windy conditions
Wind-Induced Flue or Intake Disturbance
Symptom
Boiler makes loud banging or knocking noises (kettling) during operation
Kettling Due to Scale or Sludge in Heat Exchanger
Symptom
Boiler produces fluctuating domestic hot water temperature (hot-cold-hot cycling)
Unstable DHW Temperature Control
Symptom
Boiler produces insufficient domestic hot water temperature (lukewarm water)
Low DHW Output Temperature
Symptom
Boiler runs but gas consumption seems unusually high
Inefficient Combustion or Control Settings
Symptom
Boiler runs but radiators or underfloor heating remain cold
No Heat to Emitters Despite Boiler Operation
Symptom
Boiler short cycles (frequently turns on and off) without maintaining steady temperature
Short Cycling Due to Oversizing or Control Issues
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
Boiler display shows E0 and unit will not fire
|
Communication Fault Between Main PCB and User Interface | View Details |
| E1 |
Boiler shows E1 and will not ignite, fan may start then stop
|
Ignition Failure / No Flame Detected | View Details |
| E10 |
Boiler displays E10 and will not start, often after sensor wiring work
|
Flow Temperature Sensor Fault (Open or Shorted) | View Details |
| E11 |
Boiler shows E11 and may cycle erratically, temperature readings appear incorrect
|
Return Temperature Sensor Fault | View Details |
| E12 |
Boiler displays E12 and may not respond to thermostat calls correctly
|
Outdoor Temperature Sensor Fault (Weather Compensation Systems) | View Details |
| E13 |
Boiler shows E13 and may shut down during domestic hot water demand
|
Domestic Hot Water (DHW) Temperature Sensor Fault | View Details |
| E14 |
Boiler displays E14 and may not modulate correctly, fan speed appears erratic
|
Fan Speed Feedback / Tachometer Fault | View Details |
| E15 |
Boiler shows E15 and may not respond to thermostat or zone calls
|
External Control / Thermostat Input Fault | View Details |
| E16 |
Boiler displays E16 and may shut down when switching between heating and DHW
|
Diverter Valve / 3-Way Valve Position Fault (Combi Boilers) | View Details |
| E17 |
Boiler shows E17 and may not fire even though there is a call for heat
|
Flow Switch / Flow Sensor Fault (Combi DHW or System Flow) | View Details |
| E18 |
Boiler displays E18 and may show incorrect system pressure or lock out on pressure error
|
System Pressure Sensor Fault | View Details |
| E19 |
Boiler shows E19 and may not start, often after a power surge or lightning event
|
Internal Memory / Parameter Corruption | View Details |
| E2 |
Boiler displays E2 and shuts down shortly after starting
|
Flame Loss During Operation | View Details |
| E3 |
Boiler shows E3 and will not start, fan may run briefly
|
Exhaust / Flue Temperature Overheat | View Details |
| E4 |
Boiler displays E4 and shuts down, often after running for a short period
|
Water Outlet Temperature Overheat / High Limit Trip | View Details |
| E5 |
Boiler shows E5 and will not fire, often accompanied by low or zero system pressure
|
Low Water Pressure / Low Water Sensor Fault | View Details |
| E6 |
Boiler displays E6 and shuts down, often with noisy boiling sounds inside the unit
|
Overheat Thermostat Trip / Manual Reset High Limit | View Details |
| E7 |
Boiler shows E7 and will not start, fan may not run
|
Fan / Combustion Blower Fault | View Details |
| E8 |
Boiler displays E8 and locks out, often after several failed ignition attempts
|
Gas Valve / Gas Supply Fault | View Details |
| E9 |
Boiler shows E9 and will not operate, often after a power event or wiring change
|
Polarity / Grounding / Line Voltage Error | View Details |
| EA |
Boiler displays EA and locks out, often with fan running but no ignition
|
Air Pressure Switch / Draft Proving Fault | View Details |
| EC |
Boiler shows EC and shuts down, often during long heating cycles
|
Condensate Drain / Trap Fault | View Details |
| – |
Boiler display is on but there is no response to thermostat calls (no flame icon, no fan)
|
Control Lockout or No Call for Heat Recognition | View Details |
| – |
Boiler display shows normal operation but there is no domestic hot water flow when a tap is opened (combi models)
|
No DHW Flow Detection | View Details |
| – |
Boiler does not start at all, display is blank
|
No Power / Dead Boiler | View Details |
| – |
Boiler emits a burning smell or plastic odor during operation
|
Overheating Electrical or Plastic Components | View Details |
| – |
Boiler frequently loses pressure over days or weeks without visible leaks
|
Hidden System Leak or Expansion Tank Issue | View Details |
| – |
Boiler frequently trips the household circuit breaker or blows fuses
|
Electrical Short or Overload in Boiler | View Details |
| – |
Boiler ignites but shuts down after a few seconds, with no specific error code displayed
|
Marginal Flame Detection / Weak Flame Signal | View Details |
| – |
Boiler is excessively noisy (vibration, humming, or rattling)
|
Mechanical Vibration / Loose Components | View Details |
| – |
Boiler leaking from pressure relief valve discharge pipe
|
Overpressure / Expansion System Failure | View Details |
| – |
Boiler leaking water from bottom of cabinet
|
Internal Water Leak | View Details |
| – |
Boiler locks out intermittently during windy conditions
|
Wind-Induced Flue or Intake Disturbance | View Details |
| – |
Boiler makes loud banging or knocking noises (kettling) during operation
|
Kettling Due to Scale or Sludge in Heat Exchanger | View Details |
| – |
Boiler produces fluctuating domestic hot water temperature (hot-cold-hot cycling)
|
Unstable DHW Temperature Control | View Details |
| – |
Boiler produces insufficient domestic hot water temperature (lukewarm water)
|
Low DHW Output Temperature | View Details |
| – |
Boiler runs but gas consumption seems unusually high
|
Inefficient Combustion or Control Settings | View Details |
| – |
Boiler runs but radiators or underfloor heating remain cold
|
No Heat to Emitters Despite Boiler Operation | View Details |
| – |
Boiler short cycles (frequently turns on and off) without maintaining steady temperature
|
Short Cycling Due to Oversizing or Control Issues | View Details |
No matching codes found
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