Furnace repair, diagnosis and cost

Heating faults, ignition problems, and what a repair really costs.

Will not start
Ignitor and flame sensor
Short cycling
Repair vs replace

Troubleshooting

1 article

Symptom first, cause second. Start here when something has stopped working.

Furnace Not Turning On? 7 Causes and How to Fix Each (2026) Furnace not turning on? Work the 7 real causes in order of likelihood: thermostat, power, gas, ignitor, flame sensor, board, with 2026 repair costs. Updated Jul 2026