Symptom guide
Pilot and ignition problems
Distinguish a standing pilot from electronic ignition, then choose the guide that matches no spark, no flame, or a flame that goes out.
Safety first: If you smell gas, leave without operating switches and call the gas utility or emergency services from outside. Do not repeatedly relight or reset the unit.
Start here
Identify the unit before following a procedure
Photograph the rating plate, control or display, and the exact symptom. Model generations can use different controls and code meanings even when the brand name is the same.
- Choose the heater typeGas tank, electric tank, tankless, heat pump, indirect, or RV.
- Record the exact clueCode, flash count, leak location, sound, or timing.
- Use the closest guideConfirm every model-specific step against the label or manual.
Gas
51 guidesAmerican Water Heater Pilot Won't Stay Lit
An American standing-pilot that dies is a thermocouple, FVIR, or gas valve. If you smell gas, leave.
A. O. SmithAO Smith Gas Control Valve Problems
A. O. Smith gas control faults usually come from a weak thermocouple or thermopile, an LED lockout, a clogged FVIR screen, or a failed valve.
A. O. SmithAO Smith Gas Water Heater Reset Keeps Tripping
An AO Smith gas reset that trips again points to venting, flame, or a failing control. Stop resetting.
A. O. SmithAO Smith Igniter Not Working
An A. O. Smith that won't light often has a hot-surface igniter that never glows, a control lockout, or no 120 V. How to narrow it down.
Bradford WhiteBradford White Pilot Light Reset
How to relight a Bradford White ICON correctly: wait for the status LED to go dark, then one lighting cycle. What to do if it won't hold.
Bradford WhiteBradford White Pilot Won't Light
A Bradford White pilot that never lights usually has a closed gas cock, empty LP, a dead piezo, a clogged orifice, or an ICON still in shutdown.
Bradford WhiteBradford White Water Heater Igniter Not Working
A Bradford White igniter that will not glow or spark can be power, wiring, the igniter, or control. Stop repeated starts.
Bradford WhiteBradford White Weak Pilot Signal (2 Flashes)
Two flashes on a Bradford White ICON means a weak pilot signal: the thermopile isn't making enough millivolts. Causes and next steps.
Bradford WhiteDefender Pilot Light Will Not Stay Lit
A Bradford White Defender pilot that goes out usually has a weak thermopile, a lint-clogged FVIR screen, a draft, or a failed ICON control.
GasDon't Match-Light an Electronic-Pilot Heater
Electronic-ignition water heaters should never be lit with a match; it risks delayed ignition. How to tell your ignition type and what to do.
GasDon't Purge a Water Heater Gas Line Yourself
Do not open gas fittings to release air. Learn what to do after a failed installation start and when gas odor requires immediate evacuation.
GasEco-Defender Water Heater Won't Turn On
A Bradford White Eco-Defender that won't fire usually has the pilot out, an ICON lockout, a tripped FVIR sensor, or a dead thermopile.
GasGas Burner Lights Then Dies, Pilot Stays Lit
Pilot stays lit but the main burner shuts off? Causes include a weak thermopile, a failing gas valve, a rollout or ECO trip, or a clogged FVIR screen.
GasGas Burner On but Still No Hot Water
The burner is firing but the water is still cold? Suspect the dip tube, sediment, a mixing valve, a closed hot valve, or a plumbing crossover.
GasGas Valve Electronic Fault Detected
Electronic fault detected on a Bradford White ICON or Honeywell gas control is a valve electronics lockout. What the LED count means.
GasGas Water Heater Burner Not Lighting at All
A gas burner that won't light at all usually has a closed gas cock, empty LP, a control lockout, a failed igniter, or no gas supply.
GasGas Water Heater Dead After a Power Outage
A gas water heater dead after an outage may have a 120 V lockout, a failed power-vent blower, or an extinguished pilot. What to check.
GasGas Water Heater Dead After Rain?
A gas water heater that stops after rain may have a wet FVIR screen, a drowned pilot, a soaked vent, or a wet pressure switch. Safe checks first.
GE / GeoSpringGE Water Heater Pilot Light Won't Light
A GE pilot that never lights usually has a closed gas cock, empty LP, a dead piezo, a clogged orifice, or electronic ignition with no pilot.
GE / GeoSpringGE Water Heater Pilot Will Not Stay Lit
A GE standing pilot that goes out when you release the knob usually has a thermocouple that isn't proving flame. Other causes and safe checks.
Honeywell / ResideoHoneywell Thermocouple Will Not Hold the Pilot
A Honeywell gas control that won't hold the pilot may need a thermopile, not a thermocouple. How to identify the valve type before buying parts.
Honeywell / ResideoHoneywell Water Heater Igniter No Spark
No spark from a Honeywell water heater control usually means lockout, no 120 V, a cracked electrode, or a failed module. How to narrow it.
GasPilot Dies When You Turn the Temp Dial
If the pilot goes out when you turn up the temperature dial, suspect millivolt sag, a weak valve magnet, or the main burner lifting the flame.
GasPilot Light Goes Out in Cold Weather
A pilot that goes out in cold weather is often caused by drafts, LP that won't vaporize, a sealed closet, or a clogged FVIR screen.
GasPilot Lit but Main Burner Never Opens
Pilot lit but the main burner won't come on? Check the knob and temperature setting, then suspect a weak thermopile, an ECO, or the gas control.
GasPilot Still Dies After New Thermocouple
Pilot still goes out after a new thermocouple? The part may be wrong or out of the flame, or the gas valve magnet may have failed.
GasPower-Vent Water Heater Blower Not Working
A power-vent blower that won't run keeps the gas valve closed for good reason. What to check, and why the burner must never fire without it.
RelianceReliance Water Heater Won't Light
A Reliance gas water heater that won't light usually has a closed gas cock, empty LP, a lockout, a failed igniter, or an FVIR trip.
GasReplace a Gas Water Heater Burner Assembly?
A rusty burner can signal a leaking tank rather than a bad burner. When a gas burner assembly is worth replacing, and when the tank is done.
RheemRheem Failed Ignition Lockout
A Rheem failed-ignition lockout means spark or glow didn't produce proven flame. How to read the LED or code and when a reset is appropriate.
RheemRheem Gas Control or Valve Failure
Rheem gas control faults usually come from a weak thermocouple or thermopile, an LED lockout, a clogged flame arrestor, or a failed valve.
RheemRheem Pilot Light Will Not Stay Lit
A Rheem pilot that dies is a thermocouple, FVIR screen, or gas valve — not a ritual relight. If you smell gas, leave and call a pro.
RheemRheem Thermopile Voltage Low
Low thermopile voltage on a Rheem millivolt gas valve can shut off the burner or darken the LED. Causes, what to check, and when to call a pro.
RheemRheem Water Heater Won't Light
A Rheem gas water heater that won't light usually has a closed gas cock, empty LP, a lockout, a failed igniter, or no gas supply.
RichmondRichmond Water Heater Gas Valve Problems
Richmond gas-valve faults are a weak thermopile, FVIR lockout, or a failed control. Do not purge fittings.
GasSmell Gas After Lighting the Water Heater?
A gas smell after lighting a water heater may be unburned fuel or a leak at the control. Why you should leave, not relight, and who to call.
GasSmell Gas When the Water Heater Turns On?
A gas smell only when the burner fires can mean a leak or delayed ignition. Why you should leave and call for help rather than keep cycling it.
StateState Select Gas Water Heater Troubleshooting
A State Select gas water heater that won't heat usually has a pilot, thermocouple, FVIR, or control LED fault. How to read it safely.
StateState Select Igniter Not Working
A State Select that won't light usually has a hot-surface igniter that never glows, a control lockout, or no 120 V at the valve.
StateState Select Pilot Light Won't Stay Lit
A State Select pilot that goes out when you release the knob usually has a thermocouple not proving flame, or a clogged FVIR arrestor.
UnitrolUnitrol Water Heater Gas Valve Problems
Robertshaw Unitrol standing-pilot problems usually come from the thermocouple, ECO, a weak magnet, or gas supply. Why the valve stays pro-only.
GasWater Dripping on a Gas Water Heater Burner
Water near a gas burner may be condensation, tracked water, or a tank leak. Keep wet equipment off and have the source and combustion safety assessed.
GasWater Dripping on the Water Heater Pilot
A wet pilot is T&P tracking, draft-hood drip, or a tank leak at the door. Rust at the chamber means shut gas.
GasWater Heater Flame Too High? Shut Gas Off
A lifting or sooting flame is overfire, wrong orifice, or high manifold pressure. Shut the gas cock.
GasWater Heater Made a Loud Bang? Stop
A loud bang from a gas water heater usually means delayed ignition. Why it should be shut down, and how to tell it from sediment or pipe noise.
GasWater Heater Piezo Igniter Won't Spark
A piezo igniter with no click or no spark may be a dead igniter, a wet electrode, a broken wire, or a wide gap. How to test it safely.
GasWater Heater Pilot Assembly Replacement
Pilot assembly replacement applies only to standing-pilot heaters. How to identify the actual failure first, and why gas fittings need a pro.
GasWater Heater Thermocouple Problems
A thermocouple that won't hold the pilot may be out of the flame, loose, or dead, or the gas valve magnet may have failed. Readings and next steps.
GasWet Gas Water Heater Pilot Won't Light
A gas water heater that got wet may have a drowned pilot, thermocouple, or FVIR screen, or water inside the combustion chamber. What to check.
WhirlpoolWhirlpool Pilot Light Won't Stay Lit
A Whirlpool pilot that dies is a thermocouple, dirty orifice, or FVIR — not luck. If you smell gas, leave.
GasWhy Won't My Gas Water Heater Stay Lit?
A gas water heater that lights then dies is thermocouple, thermopile, draft, or the gas valve. If you smell gas, leave.
Tankless
28 guidesBaxi Tankless Troubleshooting: Codes & Lockouts
Baxi combi cold showers often trace to ignition (E133), low pressure (E118/E119), circulation, fan, diverter, or a scaled plate exchanger.
AquaStarBosch AquaStar Tankless Troubleshooting
Bosch AquaStar tankless running cold? Causes include low flow, a clogged inlet screen, pilot or igniter faults, a flue limiter, or gas pressure.
CampluxCamplux Water Heater Not Lighting
A Camplux that won't light usually has dead batteries, empty LP, too little water flow, a wet electrode, or a tripped overheat or ODS sensor.
TakagiHow to Reset a Takagi Tankless
Reset a Takagi once after you fix the cause — power off 10–30 seconds. Do not reset a 13 remaining-flame or a flooded burner.
MareyMarey Tankless Water Heater Not Igniting
A Marey gas tankless that won't ignite usually has dead batteries, too little water flow, an LP supply problem, or an E1 ignition lockout.
NavienNavien Constantly Running: Recirc or Leak
A Navien that never seems to stop is usually the recirculation pump. If the burner itself keeps firing, suspect a stuck flow sensor or a leak.
NavienNavien E003: Ignition Failure Lockout
Navien E003 means ignition failure: the unit tried to light and never proved flame. Common causes, a safe reset, and when to call a pro.
NavienNavien Goes Cold After a Few Minutes
A Navien that goes cold after a few minutes usually has low flow, a recirculation cold slug, flame loss (E012), or scale overheating (E016).
NavienNavien Knocking Noise: What It Means
Distinguish when a Navien knocks: during ignition, water flow, or heating. Record the pattern and recognize when the unit needs service.
NoritzNoritz Code 11: Ignition Failure
Noritz code 11 means ignition failure: the unit tried to light but never proved flame. Common causes, a safe reset, and when to call a pro.
NoritzNoritz Code 12: Flame Failure
Noritz code 12 means flame failure: the burner lit, then lost flame. Common causes like gas supply and venting, and when repeats need a pro.
NoritzNoritz Tankless With No Hot Water
A Noritz with no hot water usually has no 120 V, no flow signal, a lockout code, or a gas or ignition fault. Read the display first.
QuietsideQuietSide Tankless Water Heater Problems
QuietSide tankless and combi units fail on ignition, fan or pressure switch, low loop water, or a stuck 3-way valve. What the codes mean.
RheemRheem Code 11: Ignition Failure
Code 11 on a Rheem tankless means ignition failure: the unit never proved flame. Common causes, one safe reset, and when to call a technician.
RheemRheem Tankless Error Code 12: Flame Loss
Rheem tankless code 12 means the burner lit and then lost flame. Common causes like gas supply and venting, a safe reset, and when to stop.
RheemRheem Tankless Water Heater Flashing 11
Rheem tankless code 11 means ignition failure: no flame was proven. Common causes like a closed gas cock or dirty flame rod, and one safe reset.
RinnaiRinnai Beeping With Code 17
Rinnai code 17 on SENSEI units means a venturi blockage in the air/gas mixer. What to check first and why the gas valve should stay closed up.
RinnaiRinnai Constantly Running: Recirc or Leak
A Rinnai that seems to run nonstop is usually recirculation or freeze protection. If the burner keeps firing, suspect a flow sensor or a leak.
RinnaiRinnai Error Code 12: Flame Failure
Rinnai code 12 means the burner lit and then lost flame. Common causes like gas supply, venting, or a dirty flame rod, and when to stop resetting.
RinnaiRinnai Goes Cold After a Few Minutes
A Rinnai that goes cold after a few minutes usually has flow dropping below minimum, flame loss (code 12), or scale overheating (code 16).
RinnaiRinnai In Use Light Not On
A dark In Use light means no flow, no power, or a dead remote — the burner never started. Diagnose it.
RinnaiRinnai R53 Problems: Real Field Fixes
Common Rinnai R53 problems: vent or air faults (10), ignition or flame loss (11/12), and overheating from scale or low flow (16).
RinnaiRinnai Tankless With No Hot Water
A Rinnai with no hot water usually has no 120 V, no flow signal, a lockout code, or a gas or ignition fault. Read the display first.
TakagiTakagi Code 111: Ignition Failure
Takagi code 111 means ignition failure after three tries. Common causes like a closed gas cock or dirty flame rod, a safe reset, and next steps.
TakagiTakagi Tankless Problems: Codes & Fixes
Takagi tankless not heating? Most lockouts are air or exhaust faults (10), ignition or flame loss (11/12), or overheating from scale (14/16).
TakagiTakagi Tankless Water Heater Not Heating
A Takagi tankless that will not heat needs flow, power, gas, ignition, or scale checks. Photograph the code.
TanklessTankless Water Heater Banging? Shut It Down
A banging tankless can mean delayed ignition, scale boiling in the heat exchanger, or water hammer. How to tell which, and when to shut it down.
TanklessTankless Water Heater Clicking Noise
A clicking tankless is usually ignition spark, a gas valve solenoid, a relay, or a check valve. When clicking with no flame means stop.
RV
16 guidesAtwood Clicking But Not Lighting
Atwood/Dometic click with no flame is spark without LP, a dead ECO, or a failed solenoid. Test spark with gas off.
Atwood / DometicAtwood Water Heater Will Not Stay Lit
An Atwood/Dometic that lights and then dies is losing flame: low LP, a dirty sense electrode, an ECO trip, or an open thermal fuse.
Atwood / DometicDometic Water Heater Thermal Fuse Blown
An Atwood/Dometic thermal fuse opens from flame rollout, a blocked flue, or overheating. Find the cause before replacing it; never jumper it.
FurrionFurrion Tankless E1 Ignition Failure
Furrion tankless E1 means ignition failure: the board never proved flame. Causes include LP supply, low 12 V, spark, or the flame probe.
FurrionFurrion Tankless Water Heater Troubleshooting
A Furrion tankless that is cold or flashing E1 needs power, flow, gas, or ignition checks. Photograph the code.
GirardGirard Tankless Troubleshooting: Codes & Lockouts
Girard RV tankless not heating? Most cases are an E1/E2 ignition lockout, low 12 V, an ECO trip, a probe fault, or freeze mode. What each means.
JaycoJay Flight Heater Dead? Read the Door Badge
Jay Flight trailers use Suburban, Atwood/Dometic, or tankless heaters. Identify yours, then check the bypass, ECO, LP, 12 V, and ignition board.
OasisOasis Heater Dead? Name the Module First
On motorhomes, Oasis usually means an ITR diesel hydronic system. Cold showers trace to coolant, flame-out, 12 V, the pump, or a mixing valve.
RVRV Water Heater Fault Light On
The red light on an RV water heater switch usually means a DSI ignition lockout. What it means, one safe reset, and when to stop.
RVRV Water Heater Fires Up Then Goes Out
An RV water heater that lights and then goes out is losing flame: low LP, a dirty sense electrode, an ECO or thermal fuse, or a regulator issue.
SuburbanSuburban Igniter Clicking With No Spark
Suburban DSI click with no flame is a cracked electrode, melted wire, or lockout. Test spark with LP off.
SuburbanSuburban RV Heater Not Working on Gas
If a Suburban RV heater works on electric but not propane, record the model and ignition sequence. Leave spark and fuel-system tests to a technician.
SuburbanSuburban SW10DE Troubleshooting Guide
Suburban SW10DE not heating on gas or electric? Check the ECO, bypass valves, shore power, DSI board, and igniter, starting with a full tank.
SuburbanSuburban SW6DE Troubleshooting Guide
Suburban SW6DE not heating on gas, electric, or both? Check the ECO, bypass valves, shore power, and DSI ignition, and never heat an empty tank.
SuburbanSuburban Tankless Troubleshooting
A Suburban Nautilus tankless not heating usually has an E1/E2 ignition lockout, low flow, low 12 V, an overheat code, or freeze damage.
TrumaTruma AquaGo Problems: Field Fixes
AquaGo no-heat is 12V, LP, the water filter, freeze lock, or ignition — not a generic RV tank. Decode it.
Troubleshooting
23 guides5 Flashes on Water Heater: What It Means
Five flashes is a brand-specific code — usually the upper element on electric, or a gas-valve/false-pilot fault. Decode it before you reset.
AERCOAERCO Water Heater Troubleshooting
AERCO Innovation or SmartPlate not making hot water? Lockouts usually trace to condensate, flow, ignition, or scale. Safe checks before calling a pro.
A. O. SmithAO Smith Blinking Green Light Codes
A slow green blink on an A. O. Smith gas valve is often normal. Two or more flashes is a fault code. How to count the pattern and read it.
A. O. SmithAO Smith Blinking White Light
A white or pale LED blinking on an A. O. Smith gas valve can be normal, a call for heat, or a lockout. How to tell them apart from the count.
A. O. SmithAO Smith Water Heater Humming Noise
An A. O. Smith humming can be a transformer, element, gas valve solenoid, or hybrid compressor. Match the sound to when it happens.
Bradford WhiteBradford White No Status Light
A dark Bradford White status light can mean the control is off, a dead thermopile, a failed ICON, or no 120 V on power-vent models.
TroubleshootingBrand-New Water Heater Making a Popping Noise
Day-one popping is air, pipe expansion, delayed ignition, or debris — not a 12-year tank. Name the sound.
HTP / PhoenixHTP Phoenix Problems: Lockout to Leak
Phoenix lockouts are condensate, ignition, sensors, or scale — not a mystery board. Run this sequence.
HTP / PhoenixHTP Water Heater Troubleshooting Steps
HTP Phoenix and SuperStor failures follow a short list: ignition, condensate, sensors, scale. Run these checks.
TroubleshootingNo Hot Water After Flushing the Tank
Cold showers after a flush are a dry-fire, tripped ECO, out pilot, or a breaker. Do not reset empty.
PolarisPolaris Water Heater Problems: Real Fixes
Polaris condensing water heater lockouts usually involve blocked condensate, hot-surface ignition, the blower, or scale. Safe checks first.
RelianceReliance Status Light Not Blinking
A dark Reliance status light can mean the pilot is out, a dead thermopile, the control is off or failed, or no power on electric models.
RheemRheem Water Heater Keeps Turning Off
A Rheem that heats and then shuts off has tripped a safety: an ECO, FVIR, thermopile, pressure switch, or tankless lockout. How to find which.
RheemRheem Water Heater No Status Light
A dark Rheem status light can mean no 240 V, a failed thermostat or ECO on electric models, or a pilot, thermopile, or control fault on gas.
RheemRheem Water Heater Not Heating
A Rheem not heating needs different checks for gas and electric: breaker, ECO, elements, and thermostat, or pilot, FVIR, and gas control.
RichmondRichmond Water Heater Has No Hot Water
A Richmond with no hot water needs a different check for gas and electric: breaker, ECO, element, or thermostat versus pilot, FVIR, or control.
StateState Select Water Heater No Hot Water
A State Select with no hot water needs different checks for electric and gas: breaker, ECO, and element versus igniter, FVIR, and gas control.
VaughnVaughn Hydrastone Water Heater Problems
Vaughn no-heat is the coil, sensor, or zone — not a pilot. A wet O-ring flange is a repair; a wet shell is not.
TroubleshootingWater Heater Burning Smell: Shut It Down
A burning smell from a water heater can mean scorched wiring, an overheated thermostat, hot insulation, or delayed ignition. When to shut it down.
TroubleshootingWater Heater Buzzing Noise: What It Means
A buzzing water heater may be a transformer, element, gas valve solenoid, blower, or the breaker. How to identify the source and what it means.
TroubleshootingWater Heater Hissing After a Shower?
Hiss after a shower is sediment on the element or burner, a simmering T&P, or steam from a dry-fire. Not normal.
TroubleshootingWater Heater Shuts Off After 5 Minutes
A 5-minute shutdown is flame rollout, ECO, tankless min-flow, or overheat — not a generic lockout. Stop resetting it.
TroubleshootingWater Heater Temperature Control Dead
A water heater temperature control that does nothing may be an ECO lockout, a failed thermostat, a gas valve fault, or a mixing valve.