Water heater pilot light won't stay lit: causes, and who should relight it

What a pilot and a thermocouple are doing

On many gas water heaters a small flame, the pilot, stays lit to ignite the main burner whenever the water needs heating. Beside it sits a sensor, usually a thermocouple, that produces a tiny electrical signal while it is hot, and that signal holds the gas valve open. If the sensor cools or fails, the valve closes and the gas stops. So when a pilot will not stay lit, the heater is often doing its job, because it refuses to feed gas into a house when it cannot confirm a flame.

That makes this a safety question as much as a comfort one. A pilot that goes out while the valve stays open would be dangerous. One that goes out and shuts the gas off is only a nuisance, and the rest of this guide covers why it happens and who should handle it.

Who should relight it

We give no relight steps, because we have no manufacturer source for your heater and the steps differ between models. The label on the heater is written for that exact unit, so use it.

What we can source is who should do the relighting. DTE’s gas safety page says: “Contact a licensed professional if the pilot flame of an appliance goes out. The professional should relight the appliance for your safety.” That is the utility’s own advice to its customers, so a pilot that keeps going out is a reason to book a visit rather than to keep trying at home. DTE does not ask you to call the utility to relight it; it says to use a licensed professional.

Common causes, in plain terms

No Michigan data says which cause is most common, so these are in no particular order.

A thermocouple that is worn or coated cannot produce its signal. It is a small part and, in general, a short repair.

A disturbed flame is another. A draft, a blocked or poorly sloped vent, or a dirty pilot opening can change how the flame sits against the sensor. Because a gas heater’s exhaust has to leave the house, a plumber looking at a pilot that will not stay lit should check the exhaust is leaving properly, not just replace a part.

The gas supply can also be interrupted or low. A shutoff valve left partly closed, a problem at the regulator or a utility interruption can starve the pilot.

Finally the gas control valve itself may be failing and unable to hold the pilot open even when everything else is sound. That is a bigger repair and can change the repair-versus-replace maths, covered on the water heater repair page and in the repair or replace tool.

One blown-out pilot after a draft or a gas interruption is a different case from one that fails every few days, so tell the visiting professional which you have.

If you smell gas

Stop reading and leave. DTE says to leave the area immediately, then from a safe location call 911 and the DTE Gas Leak Hotline at (800) 947-5000, which is free and open at all hours. Do not try to find the leak, and do not use electrical equipment, phones, switches or an open flame inside. Stay out until first responders or DTE say it is safe. The number (800) 477-4747 that gets posted as the gas line is DTE’s electric outage line.

If Consumers Energy supplies your gas, its guidance is to go to a safe place, call 911, then call 800-477-5050, which is open at all hours. Our emergency plumber page covers the rest of the emergency checklist, and the gas line page covers work on the piping itself.

Which licenses cover gas water heater work

Michigan splits this work in a way that catches people out. According to LARA’s mechanical FAQ, replacing a gas water heater calls for a Michigan mechanical license, either HVAC equipment or gas piping and venting, and a Michigan plumbing contractor’s license, with both a mechanical permit and a plumbing permit. We read that FAQ through search summaries, so confirm it with LARA before relying on it for a specific job. Pages that say any plumber can swap a gas heater leave that detail out.

A repair inside the heater’s working parts is a different question from a replacement, and our sources do not say which license a given repair needs. Ask the company, and look the license number up on LARA’s lookup. The guide on finding a licensed plumber walks through it.

If the visit ends in a replacement, that needs a permit. Sterling Heights says a water heater installation requires a plumbing permit, and Delta Township lists a water heater change out as a project that always requires one. See water heater permits.

What a repair costs

Our estimate for a water heater repair in Michigan is $160 to $805 per repair, a model and not a quote, and only one Michigan company we read publishes a repair price. A pilot or thermocouple call sits at the simple end of any repair list, but no source gives a figure for that one job.

The cost of getting someone to the house is what we can show. Five Michigan plumbing companies publish a service-call, trip or diagnostic fee, and together they run from free to about $100 (read Oct 19, 2026). Some of those fees are credited to the repair, so ask whether yours is. These are published prices, not quotes.

If the visit ends in a replacement, the permit is a small line next to the unit. Of the Michigan permit forms we read directly, seven list a water heater line item, with a median of $30 and a range of $5 to $70, and several add an application fee and a final inspection fee.

Scalding and temperature while you are at it

While a professional is at the heater, ask what the thermostat is set to. The Consumer Product Safety Commission advises 120 degrees Fahrenheit and says 140 degree water can burn in six seconds and 130 in thirty. The Department of Energy likewise says lowering from 140 to 120 degrees can reduce the risk of scalding, though people with weakened immune systems or chronic lung conditions may prefer to keep 140. With a young child or an older adult in the house, that is worth a minute of the conversation.

When the heater is old

The Department of Energy’s figures, seen in a search summary, put storage tank heaters at roughly 10 to 15 years. If yours is in that range and the pilot is failing, ask the professional whether repair is sensible. The next decision is covered in how long a water heater lasts and in the comparison of tankless and tank water heaters.