Rv Water Heater Lights Then Goes Out
You flip the switch, hear the click-click-click, watch the flame catch for two seconds, and then it dies. The RV water heater lights then goes out. No hot water, no obvious reason, and a growing list of things you'd rather do with your weekend.
The good news is that most causes are simple. Suburban and Dometic, the two biggest names in RV water heaters, build their ignition systems around the same core parts. A flame sensor, a gas valve, a control board, and an igniter.
When one of those pieces misbehaves, you get the same symptom. As of 2026, the troubleshooting flow has barely changed, which means the fix is well understood. Let's walk through it.
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Quick Answer
Your RV water heater lights then goes out because the flame sensor is dirty. Clean it with fine sandpaper or steel wool. Check the spark gap at 1/8 inch.
Confirm propane pressure around 11 inches water column. Most fixes take under 15 minutes.
The Most Likely Culprit (Flame Sensor)
The flame sensor is a small metal rod that sits directly in the burner flame. Its job is to confirm that a flame is actually burning. When the rod gets hot, it sends a tiny electrical signal back to the control board.
That signal tells the board to keep the gas valve open.
A dirty flame sensor can't send that signal properly. Carbon, soot, and oxidation build up on the rod and act like insulation. The flame looks normal.
The burner sounds normal. But the control board never gets the message, so it shuts the gas off after a few seconds.
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This one part is responsible for most "lights then goes out" problems we see in RV forums and manufacturer service bulletins. The fix is cheap and quick. Cleaning it takes about five minutes.
How can you tell if it's the sensor? Watch the flame. If it lights for two or three seconds and then cuts out, that's the classic symptom.
The board stops sparking as soon as the flame lights, then kills the gas when the sensor doesn't respond. If that matches what you're seeing, skip ahead to the fix section.
Core Explanation: How the Ignition System Actually Works
Before you start guessing, it helps to understand what happens inside the heater. There are two types of ignition systems in RVs.
Standing Pilot Systems vs. Direct Spark Ignition
Standing pilot systems are mostly found in older RVs. A small pilot flame burns all the time. When you call for hot water, that flame lights the main burner.
A thermocouple measures the pilot's heat and keeps the gas valve open. If the pilot goes out, the thermocouple cools down, the voltage drops, and the valve closes.
Direct Spark Ignition (DSI) is what modern Suburban and Dometic models use. There's no standing pilot. When you turn on the water heater, the control board opens the gas valve and starts sparking.
Once the flame sensor confirms the burner is lit, the sparking stops. If there's no confirmation, the board tries again. After three failed attempts, it locks out.
What the Flame Sensor Does (And Why It Matters)
The flame sensor works on a principle called flame rectification. It sends a very small electrical current through the flame. The control board measures that current in microamps.
A clean, properly positioned sensor generates a strong signal. A dirty one generates a weak or broken signal.
Suburban service documentation typically references a minimum flame sense current around 1.5 to 2.5 microamps. A healthy sensor will often read 4 to 6 microamps. When the reading drops too low, the board assumes the flame failed and closes the gas valve.
That's why you see the flame die even though nothing looks wrong.
The Lockout Sequence (Why It Stops Trying)
Here's a detail that confuses a lot of owners. When your heater clicks, fails, and goes silent, it's not broken. It's locked out.
The control board always gives the system three chances to light. After the third failed attempt, it stops trying and waits for a reset.
To reset the system, turn the water heater off at the wall switch. Wait 10 to 15 seconds. Turn it back on.
This clears the lockout and starts a fresh cycle. If the underlying problem is still there, it'll lock out again. But understanding this keeps you from assuming the whole unit is dead.
The Decision Tree: Diagnose Step by Step
Now let's figure out which part is causing your issue. Work through these steps in order. Each step should take less than a minute.
Step 1: Confirm Your Propane Supply
Start with the basics. Check that the propane tank isn't empty and the valve is fully open. Then test a stove burner.
If the stove won't light, the problem is upstream of the water heater. Also check the propane regulator. Cold weather can cause it to freeze or stick, which produces weak or inconsistent gas flow.
Step 2: Listen to the Click Pattern
Turn on the water heater and stand close to it. The clicking is the igniter sparking. Pay attention to how long it clicks and what happens after.
| What You Hear | What It Means | Most Likely Cause |
|---|---|---|
| Clicking with no flame | No gas reaching the burner | Empty tank, closed valve, blocked orifice |
| Flame lights, dies in 2 to 3 seconds | Flame sensor isn't confirming | Dirty or corroded flame sensor |
| Flame lights, dies in 10 to 15 seconds | Weak gas flow or sensor signal | Regulator issue or failing thermocouple |
| One click then silence | Control board isn't finishing its cycle | Bad board or loose wiring |
| Full cycle of clicking, then silence | Three attempts failed, lockout | Any of the above, now locked out |
Step 3: Flame Dies in 2 to 3 Seconds
If the flame lights and dies quickly, focus on the flame sensor. Go to the cleaning steps in the next section. This is the most common path by far.
Step 4: Flame Dies in 10 to 15 Seconds
If the flame sticks around longer, check gas flow. Look at the regulator for frost or sticking. Check for wind blowing the flame away from the sensor.
On older standing pilot models, also check the thermocouple. It might be worn out or not positioned close enough to the pilot flame.
Step 5: No Flame At All
If you hear clicking but never see a flame, gas isn't reaching the burner. Check the gas valve on the tank. Then inspect the burner tube.
Spiders love to build nests inside the burner tube, and those nests block gas flow completely.
Step 6: One Click Then Silence
This is less common. If the heater makes one attempt and stops, the control board may be failing. Check the wiring connections first.
Loose terminals can cause the same symptom. If the wiring is solid, the board likely needs replacement.
How to Fix It (With Tools You Probably Already Own)
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You don't need a mechanic for most of these fixes. You need a multimeter, fine sandpaper or steel wool, a small wire brush, and maybe some compressed air.
Clean the Flame Sensor
Turn off the water heater and close the propane tank valve. Remove the exterior access panel. The flame sensor is a metal rod near the burner.
Pull it out of its bracket or unscrew it, depending on your model. Gently rub it with fine sandpaper or steel wool until the rod looks shiny. Don't use a file.
You just want to remove the carbon buildup, not the metal.
Wipe it clean with a rag and reinstall it. Restore gas and power. Test the heater.
In our research, this fixes the issue in most cases.
Check and Adjust the Spark Gap
If cleaning doesn't work, check the spark gap. The igniter should sit about 1/8 inch from the burner tube. Too far, and the spark won't reach the gas.
Too close, and the spark can ground out before igniting anything. Adjust it gently with needle-nose pliers.
Clear the Burner Tube and Orifice
Remove the burner tube from the heater. Look through it toward the orifice. If you see webs, dirt, or debris, blow it out with compressed air.
Check the orifice itself for clogging. A tiny piece of debris can cut off enough gas to prevent ignition.
What to Do About Wind and Weather
Wind can blow the flame away from the sensor, which makes the board think the flame failed. Make sure the exterior access panel is properly installed and sealed. Some RV owners add a simple wind guard in exposed areas.
If the problem only happens on windy days, this is likely your culprit.
Test the Control Board
If you've cleaned everything and the heater still locks out, test the control board. You'll need a multimeter to check for voltage at the gas valve during an ignition attempt. If the board sends power but the valve doesn't open, the valve is bad.
If the board doesn't send power at all, the board is bad. Replacement boards run $80 to $200 depending on your model.
Mistakes That Waste Your Time (And Money)
The biggest mistake is replacing parts before cleaning. A new control board won't help if the flame sensor is dirty. A new gas valve won't help if the burner tube is blocked.
Work through the diagnosis in order.
Another common mistake is forgetting the propane valve. It sounds obvious, but plenty of people spend an hour troubleshooting a heater that never got gas. Test the stove first.
Don't bypass the safety system. If your heater locks out repeatedly, find the root cause. Don't jump wires, and don't disable the sensor.
Those shortcuts can create a serious fire hazard.
When to Call a Pro (Safety Rules You Don't Break)
Propane is safe when handled correctly. It's dangerous when you ignore the warning signs. If you smell gas near the water heater, stop immediately.
Turn off the propane at the tank. Open the windows. Don't use any switches or flames until the area airs out.
Call a professional if you've done the basic cleaning and the problem persists. Also call if you see signs of a gas leak, a cracked burner, or rusted gas lines. This is worth repeating: the safety system in your RV water heater is there for a reason.
Per the National Fire Protection Association, propane systems in RVs must shut off automatically if a flame isn't confirmed. That's the feature doing its job.
Most RV water heaters built after the early 2000s follow the RVIA standards for venting and combustion safety. The RV Industry Association publishes guidebooks for proper maintenance. If you're ever unsure, that's a good place to start.
Frequently Asked Questions
Why does my RV water heater light then go out after a few seconds?
The flame sensor is almost always the reason. It gets coated in carbon or oxidation, which blocks the tiny electrical signal it sends to the control board. The board thinks the flame failed, closes the gas valve, and the heater shuts down.
Cleaning the sensor fixes it.
Can I clean the flame sensor without removing the whole heater?
Yes. You only need to remove the exterior access panel to reach the burner area. The flame sensor sits near the burner.
You can clean it in place with fine sandpaper or steel wool. Just make sure the propane is off first.
How do I reset my RV water heater after it locks out?
Turn the water heater off at the switch. Wait 10 to 15 seconds. Turn it back on.
That clears the lockout and starts a fresh ignition cycle. If it locks out again, the underlying problem still needs to be fixed.
Why does my water heater work on electric but not on propane?
The electric side and the propane side are separate systems. If electric works but propane doesn't, the issue is in the gas system. Start by checking the propane supply, then move to the burner tube and flame sensor.
Is it safe to keep trying to light my water heater if it keeps going out?
No. If it fails three times, the control board locks out for a reason. Repeatedly resetting it without fixing the issue will not help.
It can also flood the burner area with unburned propane over time. Stop, diagnose, and fix the root cause first.
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