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What to do if…
you suddenly have no hot water and your water heater shows an error or warning light

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy USA guide

Short answer

First check for danger: if you smell gas, hear hissing, see signs of a gas leak, or a carbon monoxide alarm sounds, leave immediately and call 911 or your gas utility emergency line from outside or another safe location. If there are no danger signs, photograph the error light or code and arrange service with your property manager, landlord, warranty provider, licensed plumber, or HVAC service.

Do not do these things

  • Do not stay inside to investigate if you smell gas, hear hissing, or a carbon monoxide alarm sounds.
  • Do not use light switches, doorbells, garage door openers, appliances, flashlights, matches, lighters, or vehicles near a suspected gas leak.
  • Do not use a phone in or near the suspected leak area; call only once you are away from the area.
  • Do not keep resetting or restarting a heater that faults again.
  • Do not relight a pilot, remove covers, open panels, force controls, or use tools unless the manufacturer’s instructions are clear, the step is external, and there are no gas or carbon monoxide warning signs.
  • Do not ignore headache, dizziness, nausea, weakness, confusion, sleepiness, or shortness of breath near a fuel-burning appliance.
  • Do not use an oven, grill, charcoal burner, camp stove, unvented heater, generator, or vehicle to make heat or hot water while you wait.

What to do now

  1. Do a fast safety scan.

    • If you smell rotten eggs, hear hissing, see a damaged gas line, or suspect a gas leak, get everyone out without touching switches or devices. From a safe place, call 911 or your gas utility emergency line.
    • If a carbon monoxide alarm is sounding, or anyone feels suddenly unwell near the heater, get into fresh air immediately and call 911.
    • Do not go back inside until emergency responders or the utility say it is safe.

  2. Keep the heater area stable if there are no danger signs.

    • Stop using hot water for now.
    • Keep people, pets, storage, paper, rags, paint, gasoline, cleaners, and other flammable items away from the heater.
    • Leave clear access to the heater for maintenance staff, emergency responders, or a technician.

  3. Record what you can see without opening anything.

    • Take photos of the error code, light pattern, control panel, make, model, serial label, and any visible leak.
    • Write down when the hot water stopped, whether there was a recent outage, storm, leak, flood, repair visit, or maintenance visit, and whether the heater is gas, electric, propane, tank, or tankless.

  4. Do only external no-tools checks if the area is dry and safe.

    • For an electric water heater, look at the electrical panel for a tripped breaker. Do not touch the panel with wet hands, while standing in water, or if water is near wiring or outlets. If you reset a breaker once and it trips again, stop.
    • For a gas water heater, if there is no gas smell or hissing, check whether other gas appliances are working. If no gas appliance works, contact the utility from a safe place.
    • Look for water around the tank, drain pan, pipes, or nearby floor. If water is actively leaking and it is safe to reach, turn the cold-water supply valve to the heater clockwise until it stops. If water is near electrical parts, step back and call for help.

  5. Contact the right person and send the photos.

    • If you rent, report “no hot water plus water heater error light or code” to your landlord, property manager, or emergency maintenance line.
    • If you own, contact a licensed plumber or HVAC service. If the heater is under warranty or a service plan, contact that provider.
    • Tell them whether there is gas smell, hissing, a carbon monoxide alarm, water on the floor, a tripped breaker, or an error code.

  6. Treat any reset as a stopgap, not a repair.

    • Only use a single clearly labelled external reset if the manual or instructions on the unit say to do it and there are no gas, carbon monoxide, leak, or electrical danger signs.
    • If the heater faults again, stop and wait for service.

What can wait

You do not need to decode the warning light perfectly, order parts, drain the tank, choose a replacement heater, relight a pilot, inspect venting, test gas valves, or decide repair versus replacement right now. The immediate job is safety, documentation, and getting the right person involved.

Important reassurance

Many water heaters shut down because a safety control, sensor, ignition system, venting check, temperature limit, or power condition is not right. Treating the warning as real, avoiding repeated resets, and arranging qualified help is a calm and safe first response.

Scope note

These are first steps only. Later decisions about repair, replacement, warranty, habitability, landlord obligations, electrical work, gas work, venting, or code compliance may need help from a qualified technician, utility, property manager, local authority, or other specialist.

Important note

This is general information, not emergency, legal, medical, electrical, plumbing, HVAC, gas-safety, tenancy, or professional advice. If you suspect a gas leak or carbon monoxide exposure, leave first and contact emergency services or your gas utility from a safe location.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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