Lochinvar Water Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E001
Lochinvar condensing gas water heater will not ignite; display shows E001 and burner never lights.
Ignition Failure Lockout
E002
Lochinvar water heater attempts to light but shuts down quickly; display shows E002 and retries ignition several times.
Flame Failure / Loss of Flame Signal
E003
Unit displays E003 and shuts down; blower may run briefly but burner does not light.
Pressure Switch / Air Proving Failure
E004
Lochinvar water heater shows E004 and will not fire; fan may run continuously.
Exhaust / Flue Temperature High or Vent Blocked
E005
Display shows E005 and unit shuts down; may occur during long hot water draws.
Outlet Water Temperature High / Overheat
E006
Unit displays E006 and will not operate; may occur immediately at startup.
Inlet Water Temperature Sensor Fault
E007
Lochinvar heater shows E007; unit may run briefly then shut down.
Outlet Water Temperature Sensor Fault
E008
Control displays E008 and unit locks out; may be accompanied by erratic temperature readings.
Tank Temperature Sensor / Thermistor Fault
E009
Display shows E009; unit may not respond to thermostat or demand signal.
Thermostat / External Control Input Fault
E010
Lochinvar water heater shows E010 and shuts down; may occur during high demand.
High Limit Switch Trip / Manual Reset Limit Open
E011
Display shows E011; unit may not power up fully or may reboot intermittently.
Low Voltage / Power Supply Fault
E012
Lochinvar heater displays E012 and shuts down; fan may continue to run.
Combustion Fan / Blower Fault
E013
Display shows E013; unit may short-cycle or fail to maintain temperature.
Flow Sensor / Flow Switch Fault
E014
Lochinvar water heater shows E014; burner may shut down unexpectedly.
Gas Valve / Gas Train Fault
E015
Display shows E015; unit may not respond to user inputs or may freeze on one screen.
Control Board / EEPROM Fault
E016
Lochinvar heater shows E016; may be associated with condensate leakage or gurgling sounds.
Condensate Drain / Trap Fault
E017
Display shows E017; unit may shut down during operation with no obvious mechanical issue.
Internal Communication Error (Display to Main Board)
E018
Lochinvar water heater shows E018; may be associated with low water pressure or air in system.
Low Water Level / Low System Pressure (Hydronic or Indirect Systems)
E019
Display shows E019; unit may lock out after several failed ignition attempts.
Ignition Lockout (Exceeded Retry Count)
E020
Lochinvar heater shows E020; may be associated with recirculation pump not running.
Pump Output / Recirculation Pump Fault
Symptom
Condensate water dripping from vent joints on a Lochinvar condensing water heater.
Improper Vent Condensate Management
Symptom
Intermittent hot water; Lochinvar heater cycles on and off rapidly, causing temperature swings at fixtures.
Short Cycling / Flow Modulation Issue
Symptom
Lochinvar electric water heater trips the circuit breaker or blows fuses.
Electrical Short / Overcurrent
Symptom
Lochinvar water heater burner is very noisy, with roaring or whistling sound during operation.
Combustion Instability / Improper Gas-Air Mixture
Symptom
Lochinvar water heater cycles off on high limit during long hot water draws, then restarts after cooling.
Inadequate Flow / Overheating Under Load
Symptom
Lochinvar water heater display is blank or unreadable, but unit still heats water.
Display Module Failure
Symptom
Lochinvar water heater does not start; no lights or display, completely dead.
No Power / Control Not Energized
Symptom
Lochinvar water heater fan runs but burner does not light; no error code displayed.
Ignition Sequence Incomplete
Symptom
Lochinvar water heater frequently goes out on pilot (standing pilot models) during windy conditions.
Pilot Flame Instability / Draft Interference
Symptom
Lochinvar water heater makes loud popping or rumbling noises during heating.
Lime Scale Buildup on Heat Exchanger or Tank Bottom
Symptom
Lochinvar water heater produces a rotten egg or sulfur smell in hot water only.
Bacterial Contamination / Anode Reaction
Symptom
Lochinvar water heater shows signs of rust around the anode rod port or hot outlet connection.
Anode Rod Depletion / Localized Corrosion
Symptom
Lochinvar water heater T&P relief valve is dripping or discharging water periodically.
Excessive Temperature or Pressure / T&P Valve Operation
Symptom
No hot water from Lochinvar gas water heater; pilot will not stay lit (standing pilot models).
Thermocouple Failure
Symptom
Water is too hot from Lochinvar water heater, even at low thermostat settings.
Thermostat / Temperature Control Failure
Symptom
Water leaking from the bottom of a Lochinvar tank-type water heater.
Tank Corrosion / Internal Tank Leak
Symptom
Water leaking from the top of a Lochinvar water heater around piping connections.
Top Fitting / Dielectric Nipple Leak
Symptom
Water not hot enough from Lochinvar water heater; runs out of hot water quickly.
Insufficient Heating / Capacity or Control Issue
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E001 |
Lochinvar condensing gas water heater will not ignite; display shows E001 and burner never lights.
|
Ignition Failure Lockout | View Details |
| E002 |
Lochinvar water heater attempts to light but shuts down quickly; display shows E002 and retries ignition several times.
|
Flame Failure / Loss of Flame Signal | View Details |
| E003 |
Unit displays E003 and shuts down; blower may run briefly but burner does not light.
|
Pressure Switch / Air Proving Failure | View Details |
| E004 |
Lochinvar water heater shows E004 and will not fire; fan may run continuously.
|
Exhaust / Flue Temperature High or Vent Blocked | View Details |
| E005 |
Display shows E005 and unit shuts down; may occur during long hot water draws.
|
Outlet Water Temperature High / Overheat | View Details |
| E006 |
Unit displays E006 and will not operate; may occur immediately at startup.
|
Inlet Water Temperature Sensor Fault | View Details |
| E007 |
Lochinvar heater shows E007; unit may run briefly then shut down.
|
Outlet Water Temperature Sensor Fault | View Details |
| E008 |
Control displays E008 and unit locks out; may be accompanied by erratic temperature readings.
|
Tank Temperature Sensor / Thermistor Fault | View Details |
| E009 |
Display shows E009; unit may not respond to thermostat or demand signal.
|
Thermostat / External Control Input Fault | View Details |
| E010 |
Lochinvar water heater shows E010 and shuts down; may occur during high demand.
|
High Limit Switch Trip / Manual Reset Limit Open | View Details |
| E011 |
Display shows E011; unit may not power up fully or may reboot intermittently.
|
Low Voltage / Power Supply Fault | View Details |
| E012 |
Lochinvar heater displays E012 and shuts down; fan may continue to run.
|
Combustion Fan / Blower Fault | View Details |
| E013 |
Display shows E013; unit may short-cycle or fail to maintain temperature.
|
Flow Sensor / Flow Switch Fault | View Details |
| E014 |
Lochinvar water heater shows E014; burner may shut down unexpectedly.
|
Gas Valve / Gas Train Fault | View Details |
| E015 |
Display shows E015; unit may not respond to user inputs or may freeze on one screen.
|
Control Board / EEPROM Fault | View Details |
| E016 |
Lochinvar heater shows E016; may be associated with condensate leakage or gurgling sounds.
|
Condensate Drain / Trap Fault | View Details |
| E017 |
Display shows E017; unit may shut down during operation with no obvious mechanical issue.
|
Internal Communication Error (Display to Main Board) | View Details |
| E018 |
Lochinvar water heater shows E018; may be associated with low water pressure or air in system.
|
Low Water Level / Low System Pressure (Hydronic or Indirect Systems) | View Details |
| E019 |
Display shows E019; unit may lock out after several failed ignition attempts.
|
Ignition Lockout (Exceeded Retry Count) | View Details |
| E020 |
Lochinvar heater shows E020; may be associated with recirculation pump not running.
|
Pump Output / Recirculation Pump Fault | View Details |
| – |
Condensate water dripping from vent joints on a Lochinvar condensing water heater.
|
Improper Vent Condensate Management | View Details |
| – |
Intermittent hot water; Lochinvar heater cycles on and off rapidly, causing temperature swings at fixtures.
|
Short Cycling / Flow Modulation Issue | View Details |
| – |
Lochinvar electric water heater trips the circuit breaker or blows fuses.
|
Electrical Short / Overcurrent | View Details |
| – |
Lochinvar water heater burner is very noisy, with roaring or whistling sound during operation.
|
Combustion Instability / Improper Gas-Air Mixture | View Details |
| – |
Lochinvar water heater cycles off on high limit during long hot water draws, then restarts after cooling.
|
Inadequate Flow / Overheating Under Load | View Details |
| – |
Lochinvar water heater display is blank or unreadable, but unit still heats water.
|
Display Module Failure | View Details |
| – |
Lochinvar water heater does not start; no lights or display, completely dead.
|
No Power / Control Not Energized | View Details |
| – |
Lochinvar water heater fan runs but burner does not light; no error code displayed.
|
Ignition Sequence Incomplete | View Details |
| – |
Lochinvar water heater frequently goes out on pilot (standing pilot models) during windy conditions.
|
Pilot Flame Instability / Draft Interference | View Details |
| – |
Lochinvar water heater makes loud popping or rumbling noises during heating.
|
Lime Scale Buildup on Heat Exchanger or Tank Bottom | View Details |
| – |
Lochinvar water heater produces a rotten egg or sulfur smell in hot water only.
|
Bacterial Contamination / Anode Reaction | View Details |
| – |
Lochinvar water heater shows signs of rust around the anode rod port or hot outlet connection.
|
Anode Rod Depletion / Localized Corrosion | View Details |
| – |
Lochinvar water heater T&P relief valve is dripping or discharging water periodically.
|
Excessive Temperature or Pressure / T&P Valve Operation | View Details |
| – |
No hot water from Lochinvar gas water heater; pilot will not stay lit (standing pilot models).
|
Thermocouple Failure | View Details |
| – |
Water is too hot from Lochinvar water heater, even at low thermostat settings.
|
Thermostat / Temperature Control Failure | View Details |
| – |
Water leaking from the bottom of a Lochinvar tank-type water heater.
|
Tank Corrosion / Internal Tank Leak | View Details |
| – |
Water leaking from the top of a Lochinvar water heater around piping connections.
|
Top Fitting / Dielectric Nipple Leak | View Details |
| – |
Water not hot enough from Lochinvar water heater; runs out of hot water quickly.
|
Insufficient Heating / Capacity or Control Issue | View Details |
No matching codes found
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