You go to take a shower after a long day on the road, and the water's ice cold. You check the water heater, and sure enough — the pilot light is out again. If your RV water heater pilot light won't stay lit, you're not alone. It's one of the most common complaints among RV owners, and the good news is that most causes are diagnosable and fixable without calling a tech.
This guide walks you through the three most common reasons an RV water heater pilot light won't stay lit, how to diagnose each one, and what parts you may need to fix it.
How the Pilot Light System Works
Before diving into causes, a quick overview helps. In a propane RV water heater, the pilot light is a small, continuous flame that ignites the main burner when the thermostat calls for heat. A component called the thermocouple (or thermopile in some models) sits in the pilot flame and generates a small electrical current. That current signals the gas valve to stay open. If the flame goes out — or the thermocouple doesn't sense it — the gas valve closes automatically as a safety measure.
That's why a pilot that lights but won't stay lit almost always points to one of three things: a faulty thermocouple, a dirty or obstructed pilot orifice, or a failing gas valve.
Cause #1: Faulty or Worn Thermocouple
This is the most common cause by far. The thermocouple is a small metal probe that sits directly in the pilot flame. Over time, it wears out, gets coated in residue, or simply fails to generate enough voltage to keep the gas valve open.
How to Diagnose It
- Light the pilot and hold the pilot button down for the full 30–60 seconds as instructed
- Release the button — if the flame goes out immediately or within a few seconds, the thermocouple is the likely culprit
- Visually inspect the thermocouple tip: it should sit directly in the pilot flame. If it's bent away from the flame or coated in white residue, that's your problem
How to Fix It
First, try cleaning the thermocouple tip gently with fine steel wool or emery cloth to remove any oxidation. If cleaning doesn't solve it, replacement is the fix. Thermocouples are inexpensive and typically take 15–30 minutes to swap out.
Parts you may need: Universal thermocouple (most RV water heaters use a standard 18–24 inch thermocouple) or a model-specific thermocouple for Suburban or Atwood/Dometic units.
Cause #2: Dirty or Clogged Pilot Orifice
The pilot orifice is a tiny opening that meters propane flow to the pilot flame. Because it's so small, it's vulnerable to dirt, spider webs, and debris — especially if your RV has been in storage. A partially blocked orifice produces a weak flame that can't heat the thermocouple enough to keep the gas valve open.
How to Diagnose It
- Observe the pilot flame when lit — a healthy pilot flame should be steady, blue, and large enough to fully engulf the thermocouple tip
- A weak, yellow, or flickering flame that barely reaches the thermocouple points to a flow restriction
- If the pilot lights but the flame looks small or lazy, suspect the orifice before the thermocouple
How to Fix It
Turn off the propane supply completely before doing anything. Use a can of compressed air to blow out the pilot tube and orifice. For stubborn blockages, a thin strand of wire or a specialized orifice cleaning tool can clear debris. Never use a drill bit or anything that could enlarge the orifice — even a slight enlargement changes the fuel-to-air ratio and creates a safety hazard.
If cleaning doesn't restore a strong flame, the orifice itself may need replacement.
Parts you may need: Pilot orifice/burner assembly for your specific water heater model (Suburban or Atwood/Dometic part numbers vary by BTU rating).
Cause #3: Failing Gas Valve
The gas valve controls propane flow to both the pilot and the main burner. It relies on the thermocouple signal to stay open. If the valve itself is failing — either mechanically or electrically — it may not hold open even when the thermocouple is working correctly.
How to Diagnose It
- If you've already replaced or confirmed a working thermocouple and cleaned the pilot orifice, but the pilot still won't stay lit, the gas valve is the next suspect
- You can test thermocouple output voltage with a multimeter — a working thermocouple should produce 25–35 millivolts when heated. If voltage is good but the valve won't stay open, the valve is faulty
- Also check for any visible corrosion or damage on the gas valve body
How to Fix It
Gas valve replacement is more involved than a thermocouple swap and requires shutting off the propane supply and disconnecting gas lines. If you're not comfortable working with gas connections, this is a job worth handing to a certified RV technician. That said, it's a straightforward repair for anyone experienced with propane systems.
Parts you may need: Combination gas valve for your Suburban or Atwood water heater model. Make sure to match the BTU rating and inlet/outlet orientation.
Other Things to Check
If none of the three causes above seem to be the issue, run through this quick checklist before going further:
- Propane supply: Is your tank low or empty? Low pressure can cause a weak pilot flame.
- Wind: Camping in a windy spot? Drafts can blow out the pilot through the exterior vent. Some owners add a wind baffle around the water heater access door.
- Bypass valves: Make sure your water heater bypass valve (used during winterization) is set correctly. A water heater with an empty tank won't operate safely.
- Thermostat setting: Ensure the thermostat is turned up — some models have a dial that can get accidentally turned down.
Safety Warnings
- Always turn off the propane supply before inspecting or replacing any components
- Allow the water heater to cool completely before touching internal parts
- Never attempt to bypass the thermocouple safety system — it exists to prevent gas buildup
- If you smell propane at any point during diagnosis, stop immediately, ventilate the area, and do not create any sparks
- If you're unsure about working with gas lines, hire a certified RV technician
Frequently Asked Questions
How long should I hold the pilot button on an RV water heater?
Hold it for a full 30–60 seconds after the pilot lights. This gives the thermocouple time to heat up and generate enough voltage to hold the gas valve open. Releasing too soon is one of the most common reasons the pilot goes right back out.
Can I replace an RV water heater thermocouple myself?
Yes — it's one of the easier DIY repairs on an RV water heater. The thermocouple is held in place by a bracket and connected with a threaded fitting. Most replacements take under 30 minutes with basic hand tools.
How do I know if my RV water heater thermocouple is bad?
The classic sign is a pilot that lights and stays on while you hold the button, but goes out as soon as you release it. You can also test it with a multimeter — a bad thermocouple will produce little to no millivoltage when heated.
Why does my RV water heater pilot light keep going out in wind?
Wind blowing through the exterior access panel can extinguish the pilot. Try positioning your RV so the water heater vent faces away from the prevailing wind, or install a wind shield around the access door opening.
Is it safe to relight an RV water heater pilot light myself?
Yes, as long as you follow the manufacturer's relighting procedure on the label inside the access panel. Always wait several minutes after the pilot goes out before attempting to relight — this allows any residual propane to dissipate.
Get the Right Parts at The RV Surplus
Whether you need a thermocouple, a pilot orifice, or a full gas valve replacement, we carry water heater parts for Suburban and Atwood/Dometic units at discount prices — with free shipping to the continental U.S.
Shop Water Heaters & Parts at The RV Surplus →
Not sure which part fits your model? Check out our RV Appliance Crossover Chart or call or text us at 574-218-0549 and we'll point you to the right part.
Still having trouble? Browse our other troubleshooting guides — including our RV Furnace Troubleshooting Guide — for more DIY help.