Giant
Giant 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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E0
The control board powers up but displays E0 and will not start the heating cycle.
Control Initialization Fault
E1
Water heater displays E1, and the burner or elements do not turn on.
Inlet Temperature Sensor Fault
E2
The display shows E2, and the unit shuts down shortly after starting.
Outlet Temperature Sensor Fault
E3
E3 error, and the burner or elements cycle erratically; water temperature is unstable.
Tank Temperature Sensor / ECO Fault
E4
E4 is displayed, and the burner will not ignite on a gas Giant water heater.
Flame Sensor / Flame Detection Fault
E5
E5 error, no ignition, and repeated clicking from the igniter on a gas model.
Ignition Failure / Igniter Fault
E6
E6 is displayed, and the burner shuts down shortly after ignition.
Flame Loss / Unstable Combustion
E7
E7 error, and the blower fan does not start on a power-vent Giant water heater.
Inducer/Blower Motor Fault
E8
E8 is displayed, and the unit locks out and will not restart until power is cycled.
High Limit / Overheat Lockout
E9
E9 error, no hot water, and the control indicates a dry-fire or low water condition.
Dry-Fire / Low Water Detection Fault
F1
F1 fault code on the display; the water heater is unresponsive to temperature adjustments.
User Interface / Keypad Fault
F2
F2 code and water temperature overshoots setpoint significantly.
Temperature Overshoot / Thermostat Calibration Fault
F3
F3 displayed; fan runs but no ignition on power-vent gas model.
Pressure Switch / Air Proving Fault
F4
F4 code; burner lights then shuts off within a few seconds.
Flame Proving Timeout
F5
F5 error and no hot water on electric Giant water heater with digital control.
Upper Heating Element Circuit Fault
F6
F6 error and limited hot water on electric Giant water heater.
Lower Heating Element Circuit Fault
F7
F7 code; fan runs continuously even when no hot water is demanded.
Stuck Relay / Fan Control Fault
F8
F8 error and control indicates sensor mismatch or configuration error.
Sensor Configuration / Type Mismatch
F9
F9 code; unit reports a communication error between the display and main control.
Communication Bus Fault
Symptom
Condensation or water pooling on top of or around the base of the water heater shortly after installation.
Normal Condensation / Cold Start Moisture
Symptom
Hot water pressure is significantly lower than cold water pressure.
Hot Outlet Restriction
Symptom
No hot water at all on gas Giant water heater – pilot will not light or stay lit (standing pilot models).
Pilot Ignition / Thermocouple Failure
Symptom
No hot water on electric Giant water heater – tank full but water remains cold.
Total Power Loss / Dual Element Non-Operation
Symptom
Water heater T&P (temperature and pressure) relief valve drips or discharges water periodically.
Excessive Pressure / Thermal Expansion
Symptom
Water heater burner backfires or makes a loud boom at ignition.
Delayed Ignition
Symptom
Water heater causes noticeable flickering lights or voltage dips when elements cycle.
High Inrush Current / Shared Circuit Issues
Symptom
Water heater cycles on and off frequently with small temperature swings.
Short Cycling / Poor Hysteresis
Symptom
Water heater does not respond to thermostat adjustments; temperature remains constant.
Thermostat / Control Non-Responsiveness
Symptom
Water heater emits a rotten egg or sulfur smell from hot water taps.
Bacterial Contamination / Anode Reaction
Symptom
Water heater fan runs but there is no ignition and no error code displayed.
Ignition Sequence Interruption
Symptom
Water heater leaking from the bottom or around its base.
Tank Rupture / Drain Valve Leak
Symptom
Water heater leaking from the top, around piping connections.
Top Fitting / Nipple Leak
Symptom
Water heater makes a high‑pitched whistling or hissing noise from the piping.
Flow Restriction / Partially Closed Valve
Symptom
Water heater making rumbling, popping, or banging noises during heating.
Sediment Boiling / Scale Buildup
Symptom
Water heater produces discolored (rusty or brown) hot water.
Corrosion / Anode Depletion
Symptom
Water heater trips the electrical breaker intermittently.
Electrical Overload / Short Circuit
Symptom
Water heater vibrates or rattles during burner or fan operation.
Combustion Fan / Burner Vibration
Symptom
Water is too hot, causing scalding at taps on a Giant water heater without an obvious error code.
Thermostat Stuck Closed / Overheating
Symptom
Water is warm but not hot enough, and runs out quickly on an electric Giant water heater.
Single Element Operation / Thermostat Miswiring
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E0 |
The control board powers up but displays E0 and will not start the heating cycle.
|
Control Initialization Fault | View Details |
| E1 |
Water heater displays E1, and the burner or elements do not turn on.
|
Inlet Temperature Sensor Fault | View Details |
| E2 |
The display shows E2, and the unit shuts down shortly after starting.
|
Outlet Temperature Sensor Fault | View Details |
| E3 |
E3 error, and the burner or elements cycle erratically; water temperature is unstable.
|
Tank Temperature Sensor / ECO Fault | View Details |
| E4 |
E4 is displayed, and the burner will not ignite on a gas Giant water heater.
|
Flame Sensor / Flame Detection Fault | View Details |
| E5 |
E5 error, no ignition, and repeated clicking from the igniter on a gas model.
|
Ignition Failure / Igniter Fault | View Details |
| E6 |
E6 is displayed, and the burner shuts down shortly after ignition.
|
Flame Loss / Unstable Combustion | View Details |
| E7 |
E7 error, and the blower fan does not start on a power-vent Giant water heater.
|
Inducer/Blower Motor Fault | View Details |
| E8 |
E8 is displayed, and the unit locks out and will not restart until power is cycled.
|
High Limit / Overheat Lockout | View Details |
| E9 |
E9 error, no hot water, and the control indicates a dry-fire or low water condition.
|
Dry-Fire / Low Water Detection Fault | View Details |
| F1 |
F1 fault code on the display; the water heater is unresponsive to temperature adjustments.
|
User Interface / Keypad Fault | View Details |
| F2 |
F2 code and water temperature overshoots setpoint significantly.
|
Temperature Overshoot / Thermostat Calibration Fault | View Details |
| F3 |
F3 displayed; fan runs but no ignition on power-vent gas model.
|
Pressure Switch / Air Proving Fault | View Details |
| F4 |
F4 code; burner lights then shuts off within a few seconds.
|
Flame Proving Timeout | View Details |
| F5 |
F5 error and no hot water on electric Giant water heater with digital control.
|
Upper Heating Element Circuit Fault | View Details |
| F6 |
F6 error and limited hot water on electric Giant water heater.
|
Lower Heating Element Circuit Fault | View Details |
| F7 |
F7 code; fan runs continuously even when no hot water is demanded.
|
Stuck Relay / Fan Control Fault | View Details |
| F8 |
F8 error and control indicates sensor mismatch or configuration error.
|
Sensor Configuration / Type Mismatch | View Details |
| F9 |
F9 code; unit reports a communication error between the display and main control.
|
Communication Bus Fault | View Details |
| – |
Condensation or water pooling on top of or around the base of the water heater shortly after installation.
|
Normal Condensation / Cold Start Moisture | View Details |
| – |
Hot water pressure is significantly lower than cold water pressure.
|
Hot Outlet Restriction | View Details |
| – |
No hot water at all on gas Giant water heater – pilot will not light or stay lit (standing pilot models).
|
Pilot Ignition / Thermocouple Failure | View Details |
| – |
No hot water on electric Giant water heater – tank full but water remains cold.
|
Total Power Loss / Dual Element Non-Operation | View Details |
| – |
Water heater T&P (temperature and pressure) relief valve drips or discharges water periodically.
|
Excessive Pressure / Thermal Expansion | View Details |
| – |
Water heater burner backfires or makes a loud boom at ignition.
|
Delayed Ignition | View Details |
| – |
Water heater causes noticeable flickering lights or voltage dips when elements cycle.
|
High Inrush Current / Shared Circuit Issues | View Details |
| – |
Water heater cycles on and off frequently with small temperature swings.
|
Short Cycling / Poor Hysteresis | View Details |
| – |
Water heater does not respond to thermostat adjustments; temperature remains constant.
|
Thermostat / Control Non-Responsiveness | View Details |
| – |
Water heater emits a rotten egg or sulfur smell from hot water taps.
|
Bacterial Contamination / Anode Reaction | View Details |
| – |
Water heater fan runs but there is no ignition and no error code displayed.
|
Ignition Sequence Interruption | View Details |
| – |
Water heater leaking from the bottom or around its base.
|
Tank Rupture / Drain Valve Leak | View Details |
| – |
Water heater leaking from the top, around piping connections.
|
Top Fitting / Nipple Leak | View Details |
| – |
Water heater makes a high‑pitched whistling or hissing noise from the piping.
|
Flow Restriction / Partially Closed Valve | View Details |
| – |
Water heater making rumbling, popping, or banging noises during heating.
|
Sediment Boiling / Scale Buildup | View Details |
| – |
Water heater produces discolored (rusty or brown) hot water.
|
Corrosion / Anode Depletion | View Details |
| – |
Water heater trips the electrical breaker intermittently.
|
Electrical Overload / Short Circuit | View Details |
| – |
Water heater vibrates or rattles during burner or fan operation.
|
Combustion Fan / Burner Vibration | View Details |
| – |
Water is too hot, causing scalding at taps on a Giant water heater without an obvious error code.
|
Thermostat Stuck Closed / Overheating | View Details |
| – |
Water is warm but not hot enough, and runs out quickly on an electric Giant water heater.
|
Single Element Operation / Thermostat Miswiring | View Details |
No matching codes found
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