Gas fireplace repair for a unit that will not light or stay lit
A gas fireplace that clicks without lighting, lights only while the control knob is held, or shuts down after the burner starts is giving a useful diagnostic clue. The cause may be a restricted pilot orifice, weak spark, worn thermocouple or thermopile, failed receiver, interrupted gas supply, control-valve fault, or a burner issue. The diagnostic scope should test the relevant ignition path before a part is recommended.
Won't light: pilot, igniter, and gas supply
If the igniter clicks but no flame appears, the spark may be missing the pilot, the pilot opening may be restricted, or gas may not be reaching the assembly. If there is no click, the fault may be the piezo igniter, electronic module, battery pack, receiver, wall switch, or low-voltage wiring. Testing each point avoids replacing an igniter when the actual fault is farther down the circuit.
Won't stay lit: thermocouple, thermopile, and valve signal
When a pilot burns only while the knob is held, the safety sensor may not be generating or transmitting the signal that keeps the gas valve open. Relevant checks may include pilot-flame contact, thermocouple or thermopile output, connections, and valve response. A pilot that stays on while the main burner does not may point instead to the switch circuit, receiver, thermopile output under load, or main valve.
Burner, logs, glass, and flame pattern
Low flame, uneven flame, soot on the glass, or black marks on ceramic logs can come from restricted burner ports, incorrect log placement, combustion-air or venting problems, or a control issue. Gas logs must sit in the pattern specified for the unit; moving them for appearance can put flame where the manufacturer did not intend it.
If you smell gas
Do not try to light the fireplace or operate switches, electronics, or flames. Evacuate immediately, then call 911 and the gas utility from outside. Contact a fireplace contractor only after emergency responders or the gas utility have cleared the property as safe.
Repair is different from installation
This page is for an existing gas fireplace with a specific fault. For a new insert, gas-log installation, whole-unit replacement, or wood-to-gas conversion, use the gas fireplace installation page instead.