Homeowner Safety Guide
If you suspect a gas leak, leave immediately, even if the smell is faint. Do not use a phone, switches, appliances, or flames in the affected area. From a safe location outside, call 911 or your gas utility's emergency line.
Leave first. Call from a safe place outside. Do not reenter until emergency responders say it is safe.
Call 911 from a safe locationCity Utilities natural gas safety guidanceDo not wait for a stronger smell or try to find the leak. Get everyone away from the building and call from a safe place. City Utilities advises moving at least 300 feet away. Its natural gas customers can call 417-863-9000 from that safe location; other customers should use their own gas utility's emergency line or 911.
Avoid lighting flames, using switches near the smell, or running the furnace again to confirm the symptom. Do not return to gather details or photos. Tell responders only what you already noticed before leaving.
After the gas utility or emergency path says the immediate gas concern is safe, a heating diagnostic can look at the furnace no-heat symptom, ignition behavior, airflow, thermostat call, and shutdown pattern. For normal no-heat symptoms without an active gas smell, start with the $95 Springfield Diagnostic. Nearby towns may cost more.
Read the furnace no-heat guide