Lennox: Pressure Switch Stuck Open
What this fault means
The inducer ran but draft was never confirmed, so the Lennox control blocks ignition.
Likely causes
- Blocked or restricted vent / intake
- Failed inducer
- Disconnected pressure tubing
- Plugged condensate trap
What you can safely check
- Replace a dirty air filter — restricted airflow causes a surprising share of furnace faults.
- Confirm registers and the outdoor unit are clear of snow, leaves and debris.
- Cycle power at the switch once and let the system retry.
Call a technician — don't keep resetting this
Pressure Switch Stuck Open is a high-severity fault. Repeated resets of a safety lockout can mask a serious problem such as a cracked heat exchanger (a carbon-monoxide risk) or a failing compressor. If you smell gas, leave and call FortisBC at 1-800-663-9911 or 911 first.
Related Lennox faults
Lennox furnace showing Pressure Switch Stuck Open?
CANRO Heating & Cooling — same-day diagnosis across Greater Vancouver. Call 604-359-1081.