Lochinvar Pool Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Pool heater will not ignite; display shows E01 shortly after a call for heat.
Ignition Failure / Ignition Lockout
E02
Heater attempts to start but shuts down with E02; blower may run briefly, no sustained flame.
Flame Loss / Flame Failure During Run
E03
Heater will not start; display shows E03 indicating pressure switch or flow issue.
Water Pressure Switch Open / Low Water Flow
E04
Heater shuts down with E04; may start briefly then stop, often related to high limit temperature.
High Limit Switch Open / Overheat Condition
E05
Display shows E05; heater will not fire and may indicate rollout or flame safeguard issue.
Flame Rollout / Rollout Switch Open
E06
Heater displays E06 and will not start; often associated with exhaust or vent temperature issues.
Flue Temperature High / Exhaust Limit Open
E07
Display shows E07; heater does not fire and may indicate an issue with the outlet water temperature sensor.
Outlet Water Temperature Sensor Fault (Open/Short)
E08
Heater shows E08; unit will not run and may indicate an inlet water temperature sensor problem.
Inlet Water Temperature Sensor Fault (Open/Short)
E09
Display shows E09; heater does not respond to thermostat changes or shows erratic temperature readings.
Thermostat / Control Sensor Error
E10
Heater displays E10; blower may not start or stops unexpectedly.
Blower Fault / Combustion Air Fan Failure
E11
Display shows E11; heater will not fire and indicates air pressure or proving switch fault.
Air Pressure Switch Open / Inducer Proving Failure
E12
Heater shows E12; may indicate low gas pressure or gas valve fault during ignition.
Gas Valve / Gas Supply Fault
E13
Display shows E13; heater may lock out and indicate ignition control or flame safeguard error.
Ignition Control Module Fault
E14
Heater displays E14; may indicate a stack flue sensor or vent temperature sensor open/short.
Stack Flue Sensor Fault
E15
Display shows E15; heater may not respond to user inputs or external controls.
User Interface / Keypad Communication Error
E16
Heater shows E16; may indicate low voltage or power supply issues to the control.
Low Line Voltage / Power Supply Fault
E17
Display shows E17; heater may short-cycle or not maintain set temperature.
Differential Temperature / Sensor Mismatch Fault
E18
Heater displays E18; may indicate internal memory or configuration fault.
Control Board Configuration / EEPROM Error
E19
Display shows E19; heater may indicate condensate or blocked drain fault on condensing models.
Condensate Drain Blocked / Float Switch Open
E20
Heater shows E20; may indicate internal flow sensor or flow switch error on certain Lochinvar models.
Internal Flow Switch / Flow Sensor Fault
Symptom
Heater cabinet shows signs of corrosion, rust streaks, or paint bubbling, especially near the base.
Corrosion from Condensate or Chemical Exposure
Symptom
Heater display is on but unresponsive; buttons do not change settings.
Keypad Failure / Stuck Buttons
Symptom
Heater display shows normal operation but pool pump is off; heater may attempt to fire without flow.
Flow Interlock Missing or Bypassed
Symptom
Heater display shows temperature much higher or lower than actual pool water temperature.
Temperature Sensor Misreading / Calibration Error
Symptom
Heater emits a strong gas smell around the unit, especially at startup.
Gas Leak or Incomplete Combustion
Symptom
Heater fan or blower is very loud, squealing, or grinding during operation.
Blower Bearing Wear / Mechanical Failure
Symptom
Heater frequently shuts down with a strong chemical smell around the unit.
Chemical Fume Ingestion / Corrosive Atmosphere
Symptom
Heater ignites with a loud boom or pop (delayed ignition).
Delayed Ignition / Gas Accumulation
Symptom
Heater is leaking water from the bottom of the cabinet.
Internal Water Leak
Symptom
Heater makes loud banging or knocking noises during operation.
Kettling / Boiling in Heat Exchanger
Symptom
Heater operates normally but causes noticeable vibration in nearby plumbing or structure.
Vibration / Resonance from Blower or Pump Flow
Symptom
Heater runs but pool water does not reach set temperature; long run times with lukewarm water.
Insufficient Heating Capacity / Underperformance
Symptom
Heater runs but then trips the house breaker or blows fuses intermittently.
Electrical Short or Overload
Symptom
Heater shuts off when the pool pump turns off, but sometimes also shuts off randomly while pump is running.
Interlock / External Control Wiring Issue
Symptom
Heater starts and stops frequently (short cycling), with only brief run times before shutting off.
Short Cycling / Improper Flow or Sizing
Symptom
Heater will not start at all; no display, no lights, completely dead.
No Power to Heater
Symptom
Soot or black staining visible around the flue outlet or on the heater cabinet.
Sooting / Incomplete Combustion
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Pool heater will not ignite; display shows E01 shortly after a call for heat.
|
Ignition Failure / Ignition Lockout | View Details |
| E02 |
Heater attempts to start but shuts down with E02; blower may run briefly, no sustained flame.
|
Flame Loss / Flame Failure During Run | View Details |
| E03 |
Heater will not start; display shows E03 indicating pressure switch or flow issue.
|
Water Pressure Switch Open / Low Water Flow | View Details |
| E04 |
Heater shuts down with E04; may start briefly then stop, often related to high limit temperature.
|
High Limit Switch Open / Overheat Condition | View Details |
| E05 |
Display shows E05; heater will not fire and may indicate rollout or flame safeguard issue.
|
Flame Rollout / Rollout Switch Open | View Details |
| E06 |
Heater displays E06 and will not start; often associated with exhaust or vent temperature issues.
|
Flue Temperature High / Exhaust Limit Open | View Details |
| E07 |
Display shows E07; heater does not fire and may indicate an issue with the outlet water temperature sensor.
|
Outlet Water Temperature Sensor Fault (Open/Short) | View Details |
| E08 |
Heater shows E08; unit will not run and may indicate an inlet water temperature sensor problem.
|
Inlet Water Temperature Sensor Fault (Open/Short) | View Details |
| E09 |
Display shows E09; heater does not respond to thermostat changes or shows erratic temperature readings.
|
Thermostat / Control Sensor Error | View Details |
| E10 |
Heater displays E10; blower may not start or stops unexpectedly.
|
Blower Fault / Combustion Air Fan Failure | View Details |
| E11 |
Display shows E11; heater will not fire and indicates air pressure or proving switch fault.
|
Air Pressure Switch Open / Inducer Proving Failure | View Details |
| E12 |
Heater shows E12; may indicate low gas pressure or gas valve fault during ignition.
|
Gas Valve / Gas Supply Fault | View Details |
| E13 |
Display shows E13; heater may lock out and indicate ignition control or flame safeguard error.
|
Ignition Control Module Fault | View Details |
| E14 |
Heater displays E14; may indicate a stack flue sensor or vent temperature sensor open/short.
|
Stack Flue Sensor Fault | View Details |
| E15 |
Display shows E15; heater may not respond to user inputs or external controls.
|
User Interface / Keypad Communication Error | View Details |
| E16 |
Heater shows E16; may indicate low voltage or power supply issues to the control.
|
Low Line Voltage / Power Supply Fault | View Details |
| E17 |
Display shows E17; heater may short-cycle or not maintain set temperature.
|
Differential Temperature / Sensor Mismatch Fault | View Details |
| E18 |
Heater displays E18; may indicate internal memory or configuration fault.
|
Control Board Configuration / EEPROM Error | View Details |
| E19 |
Display shows E19; heater may indicate condensate or blocked drain fault on condensing models.
|
Condensate Drain Blocked / Float Switch Open | View Details |
| E20 |
Heater shows E20; may indicate internal flow sensor or flow switch error on certain Lochinvar models.
|
Internal Flow Switch / Flow Sensor Fault | View Details |
| – |
Heater cabinet shows signs of corrosion, rust streaks, or paint bubbling, especially near the base.
|
Corrosion from Condensate or Chemical Exposure | View Details |
| – |
Heater display is on but unresponsive; buttons do not change settings.
|
Keypad Failure / Stuck Buttons | View Details |
| – |
Heater display shows normal operation but pool pump is off; heater may attempt to fire without flow.
|
Flow Interlock Missing or Bypassed | View Details |
| – |
Heater display shows temperature much higher or lower than actual pool water temperature.
|
Temperature Sensor Misreading / Calibration Error | View Details |
| – |
Heater emits a strong gas smell around the unit, especially at startup.
|
Gas Leak or Incomplete Combustion | View Details |
| – |
Heater fan or blower is very loud, squealing, or grinding during operation.
|
Blower Bearing Wear / Mechanical Failure | View Details |
| – |
Heater frequently shuts down with a strong chemical smell around the unit.
|
Chemical Fume Ingestion / Corrosive Atmosphere | View Details |
| – |
Heater ignites with a loud boom or pop (delayed ignition).
|
Delayed Ignition / Gas Accumulation | View Details |
| – |
Heater is leaking water from the bottom of the cabinet.
|
Internal Water Leak | View Details |
| – |
Heater makes loud banging or knocking noises during operation.
|
Kettling / Boiling in Heat Exchanger | View Details |
| – |
Heater operates normally but causes noticeable vibration in nearby plumbing or structure.
|
Vibration / Resonance from Blower or Pump Flow | View Details |
| – |
Heater runs but pool water does not reach set temperature; long run times with lukewarm water.
|
Insufficient Heating Capacity / Underperformance | View Details |
| – |
Heater runs but then trips the house breaker or blows fuses intermittently.
|
Electrical Short or Overload | View Details |
| – |
Heater shuts off when the pool pump turns off, but sometimes also shuts off randomly while pump is running.
|
Interlock / External Control Wiring Issue | View Details |
| – |
Heater starts and stops frequently (short cycling), with only brief run times before shutting off.
|
Short Cycling / Improper Flow or Sizing | View Details |
| – |
Heater will not start at all; no display, no lights, completely dead.
|
No Power to Heater | View Details |
| – |
Soot or black staining visible around the flue outlet or on the heater cabinet.
|
Sooting / Incomplete Combustion | View Details |
No matching codes found
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