Mobile Home Water Heater Pilot Light Won’t Stay Lit: What to Check
A thermocouple produces about 30 millivolts when it is hot. Below roughly 15, the gas valve shuts itself off and your pilot dies. That tiny number is why a part costing under twenty dollars is the most common reason a water heater stops making hot water.
In a manufactured home there is a second suspect that site-built houses rarely deal with, and it is the one people miss.
Quick Answer
A mobile home water heater pilot light that will not stay lit usually comes down to one of three things: a worn thermocouple, a blocked combustion air path, or a vent obstruction at the roof jack. In manufactured homes the air path is the leading cause, because the unit is sealed combustion and pulls its air from outside through a narrow concentric vent. Try relighting once, following the instructions printed on the unit. If it dies again, stop. Do not keep relighting. If you smell gas at any point, leave the home and call from outside.
Symptoms and What They Mean
The pattern tells you a lot before anyone opens a panel.
The pilot lights, burns while you hold the button, then dies the moment you release it. Classic thermocouple. The sensor is not producing enough voltage to hold the gas valve open on its own. Age, soot, or a bent tip that has drifted out of the flame.
The pilot stays lit for minutes or hours, then goes out on its own. This points away from the thermocouple and toward air or venting. The unit runs, consumes the available oxygen or fights a draft, and starves. If it happens more on windy days, look at the roof jack.
The pilot will not light at all, no flame, no smell of gas at the burner. Gas supply. On propane, check whether the tank is empty and whether the regulator has iced over, which happens in cold weather and is more common than owners expect. On natural gas, confirm the shutoff is open and other gas appliances still work.
The pilot lights but the flame is yellow, lazy, or lifting off the burner. Combustion problem. A healthy pilot flame is blue with a crisp cone wrapping the thermocouple tip. Yellow means incomplete combustion, and incomplete combustion produces carbon monoxide. Shut it down and call a professional.
It started right after new carpet, a laundry day, or a pet. Lint and dust. Covered below, and in a manufactured home closet it is the single most under-diagnosed cause.
Safe Checks You Can Do Yourself
Only these. Nothing involving the gas valve, the vent assembly, or the burner chamber.
Check the air intake screen. Water heaters built since 2003 use a flammable vapor ignition resistant design with a sealed combustion chamber and a screen or arrestor at the air inlet. That screen catches lint, dust, and pet hair. When it clogs, the flame starves and the pilot dies. In a manufactured home the heater closet is small, often shares space with the furnace, and sometimes sits next to the laundry, so it clogs faster than in a garage. You can see the screen around the base of the unit. If it looks furred over, that is your answer, and cleaning it is a professional job because it means opening the combustion area.
Look at the closet itself. Boxes, cleaning supplies, and stored blankets pressed against the unit restrict airflow. Clear a few inches all around and keep it clear.
Check the roof jack from the ground. You are looking for an obvious obstruction at the vent cap: a bird nest, packed snow, a crushed or dislodged cap. Do not climb onto a manufactured home roof. They are not built for foot traffic and you will do more damage than you fix.
On propane, check the tank gauge and the regulator. An empty tank is an embarrassing but frequent answer. A regulator with frost or ice on it in cold weather needs a technician, not a hair dryer.
Relight once, by the book. Every unit has lighting instructions printed on a label. Follow them exactly, including the wait time after turning the control to off. That wait exists to let unburned gas clear. If it lights and holds, watch it for an hour. If it dies again, you have a real fault and repeated relighting will not fix it.
When This Becomes Dangerous
Stop and treat these as emergencies.
You smell gas. Rotten egg or sulfur. Do not flip switches, do not use a phone inside, do not look for the source. Leave the home, take everyone with you, and call your gas utility’s emergency line or 911 from outside. A manufactured home is a small, tight envelope and gas concentrates fast.
The pilot flame is yellow or the burner is sooty. Incomplete combustion means carbon monoxide. Carbon monoxide has no smell. Headaches, dizziness, nausea, or symptoms that improve when you leave the home are warning signs. Get out and get medical help.
Your carbon monoxide alarm sounds. Leave first. Diagnose later. If you do not have a CO alarm in a home with any gas or propane appliance, that is the cheapest safety purchase available to you.
You see scorching, melted wiring, or soot streaks around the vent connection. The vent is not doing its job. Shut off the gas at the appliance if you can do so safely and call a professional.
The pilot keeps dying and you keep relighting it. Each relight releases a small amount of unburned gas into a sealed closet. Twice is troubleshooting. Six times is a hazard.
Gas, venting, and combustion work in a manufactured home is licensed professional territory. The consequence of getting it wrong is not a leak, it is carbon monoxide in a very small space.
What a Technician Will Check on a Mobile Home Water Heater Pilot Light
A competent tech works in a specific order, and knowing it helps you judge whether yours is guessing.
They test the thermocouple output with a multimeter. A healthy one reads roughly 25 to 35 millivolts hot. Below about 15 and it cannot hold the valve. Newer units with electronic ignition use a thermopile instead, producing around 750 millivolts, and it is tested the same way.
They inspect the pilot flame geometry. The flame should envelop the top half inch of the thermocouple tip with a steady blue cone. A flame that is lifting, split, or off target means a dirty or partly blocked pilot orifice rather than a dead sensor.
They check the air intake screen and the combustion chamber. On a sealed combustion unit this is where manufactured home calls resolve most often.
They verify draft at the vent. On a concentric direct vent assembly they confirm the intake and exhaust passages are clear and the roof jack is intact and correctly matched to the unit. A roof jack that was reused from a previous heater and never quite fit shows up here.
They check gas pressure at the valve, and on propane the regulator and tank.
Only after all of that do they condemn the gas control valve, which is the expensive part. A tech who reaches for the valve first is skipping steps.
Typical Repair Cost
Ranges below are market estimates as of August 2026 and move with labor rates and location.
| Repair | Typical cost | Notes |
|---|---|---|
| Thermocouple replacement | $75 to $250 | Part is cheap, most of the cost is the visit |
| Thermopile replacement | $150 to $300 | Electronic ignition units |
| Pilot orifice or assembly cleaning | $100 to $200 | Often bundled with a service call |
| Air intake screen service | $125 to $275 | Requires opening the combustion area |
| Vent or roof jack clearing | $150 to $350 | Higher if roof access is involved |
| Gas control valve | $300 to $600 | Get a second opinion first |
| Diagnostic visit alone | $75 to $150 | Frequently credited toward the repair |
The economic line to watch: if the unit is past ten years and the quote lands near or above $500, put that money toward replacement instead. Manufactured housing units typically run 8 to 12 years on electric and 10 to 15 on propane, and a failing gas valve on an old tank is rarely the last repair. Our guide to water heaters for mobile home setups covers what fits and what a replacement runs, and how long a water heater lasts walks through the age math.
If the unit is heating inconsistently rather than losing its pilot entirely, the diagnosis is different and why a water heater is not heating properly is the better starting point. For how the sealed vent assembly is supposed to work, see water heater venting requirements.
What This Guide Does Not Establish
The cost ranges here are estimates, not quotes. Thermocouple pricing in particular varies more by how a company structures its service call than by the part itself, which is why the same repair can be $90 in one market and $220 in another. This guide also cannot tell you whether your specific unit uses a thermocouple or a thermopile. Check the data plate or the lighting label.
Find Local Help
A pilot outage in a manufactured home is a venting and combustion diagnosis. Hire someone who works on them regularly.
- Ogden: Water heater companies in Ogden
- Weber County: Water heater companies in Weber County
- Related reading: Emergency water heater repair and what qualifies
- Emergency: Water heater emergency checklist
Frequently Asked Questions
Why does my pilot light keep going out in a mobile home but my neighbor’s site-built house never has the problem? Your unit is sealed combustion and draws air from outdoors through a narrow concentric vent. A site-built house heater usually pulls air from the room around it, so it tolerates a partly restricted path. Yours does not. Add a small closet that collects lint and a roof-mounted vent cap exposed to weather, and the same fault shows up far sooner.
Can I replace the thermocouple myself? It is a common DIY repair on paper and involves the gas control assembly in practice. On a sealed combustion unit in a manufactured home, accessing it means opening the burner area, and reassembling that seal incorrectly is a carbon monoxide risk. The part costs under twenty dollars and the labor is usually under an hour. It is not worth the risk.
How many times can I safely relight it? Once, following the printed instructions. If it fails a second time there is a fault that relighting will not resolve, and each attempt puts a little unburned gas into a closed space.
Could an empty propane tank look like a pilot problem? Yes, and it is common. No gas means no pilot. Check the tank gauge before calling anyone. Cold weather regulator icing produces the same symptom and does need a technician.
My pilot dies mostly on windy days. What does that mean? Look at the vent. A damaged, loose, or mismatched roof jack cap lets wind disturb the sealed air path. This is one of the more common findings when a replacement heater was fitted to an existing vent assembly that was not quite right for it.
Is a yellow pilot flame a problem if the heater still works? Yes. A healthy pilot is blue. Yellow indicates incomplete combustion, which produces carbon monoxide, and the fact that you still get hot water does not make it safe. Shut it down and call a professional.
Sources and Update Policy
- U.S. Consumer Product Safety Commission, water heater and flammable vapor ignition resistant design guidance. cpsc.gov
- Centers for Disease Control and Prevention, carbon monoxide poisoning prevention and symptoms. cdc.gov/carbon-monoxide
- U.S. Department of Housing and Urban Development, Manufactured Home Construction and Safety Standards, 24 CFR Part 3280. hud.gov
- U.S. Department of Energy, water heating systems and maintenance. energy.gov
Repair cost ranges reflect market estimates as of August 2026 and are reviewed twice yearly. Always follow the lighting and safety instructions printed on your specific unit.