Furnace Parts That Fail Most Often — Common Replacement Guide
Published: July 22, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
1. Capacitor — Most Common Failure
The capacitor is the most commonly replaced furnace part. Symptoms: blower motor hums but does not start, or the inducer motor does not start. Replacement cost: $200-400. Lifespan: 3-5 years. Carrying a spare capacitor (ask your technician for the correct size) can save an emergency service call.
2. Flame Sensor — Second Most Common
A dirty or failed flame sensor causes the furnace to fire but shut off after 2-5 seconds. Cleaning: $150-250. Replacement: $200-350. The most common cause is carbon buildup — regular cleaning during annual maintenance prevents this.
3. Ignitor — Common Winter Failure
Ignitors fail most often during cold weather when they are used more frequently. Cracks from thermal stress cause failure. Replacement cost: $250-450. Premium silicon nitride ignitors last longer than standard silicon carbide. Regular visual inspection during maintenance can catch cracks before failure.