What should I do if my furnace clicks but will not ignite?

What this symptom usually means

A furnace that clicks but will not ignite is usually getting partway through its startup sequence and then failing at the burner-lighting stage. That is different from a furnace that runs but blows cold air or a blower that never comes on at all. Here, the key clue is that you hear an ignition attempt, often a click every few seconds, but you do not get a steady burner flame and the home does not heat.

What you can tell from the sound and timing

If you hear clicking 1 to 3 times and then the furnace stops trying, the igniter or gas delivery is a common suspect. If it starts, lights briefly, and shuts off within a few seconds, that pattern often points more toward flame sensing than ignition itself. If you hear a small fan or hum before the clicking, the inducer motor is probably running and the failure is happening after the call for heat begins; if the display shows a lockout code after several attempts, the furnace has likely shut itself down to prevent repeated failed ignition.

What a homeowner can observe before service

Look for a blinking status light or code on the furnace cabinet display and note whether the furnace tries once or keeps cycling through multiple attempts. A tripped breaker can stop the entire sequence, but if you are specifically hearing clicks, power is often present and the problem is deeper in the ignition chain. If you smell gas, leave the building immediately and call the gas utility or emergency services from outside; do not keep testing the furnace.

What the technician usually checks on this call

A technician typically watches a full heat call from thermostat signal to inducer startup, pressure-switch proof, igniter operation, gas-valve command, flame carryover, and flame-sensor reading. On this symptom, they often inspect the igniter for cracks, measure electrical output, clean or test the flame sensor, inspect burner ports for rust or misalignment, and verify whether the gas valve is opening when it should. If the furnace is locking out, they will also read the control board fault history and compare it with live operation.

What affects repair cost

Cost depends mostly on which step of the ignition sequence is failing. Flame sensor cleaning or a simple adjustment is often on the low end of a service visit, while a new hot-surface igniter commonly falls in a typical 2025-2026 range of about $170 to $575 installed. Burner cleaning or minor ignition repairs are often roughly $170 to $575, while a gas valve or control board problem can run about $500 to $1,575+ depending on furnace model, part availability, and after-hours timing.