Furnace Flame Sensor Replacement — Quick Fix Guide

Published: July 22, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC

How the Flame Sensor Works

The flame sensor is a metal rod mounted near the burner. When the burner ignites, the flame contacts the rod, creating a small electrical current that tells the control board the flame is present. If the sensor is dirty or failed, the control board shuts off the gas supply after 2-5 seconds.

Cleaning vs Replacement

If the sensor is dirty (carbon buildup), cleaning with fine steel wool ($0) often restores function. If the sensor is cracked, corroded, or has failed electrically, replacement is needed ($20-50 part). Professional cleaning: $150-250. Professional replacement: $200-350.

Emergency Service Available

If your furnace is short-cycling due to a flame sensor issue, we provide same-day service. Most flame sensor issues are diagnosed and fixed in under 30 minutes. Call for fast, professional service.

Related Services

Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.