Code 31, pressure switch did not close or reopened during operation

Safety first: Turn off power and gas before working on the venting or pressure switch.

• Step 1 – Check vent and intake: Inspect for obstructions, sagging vent pipes holding water, or disconnected joints.
• Step 2 – Clear condensate: Clean the condensate trap and drain line. Ensure proper slope on horizontal vent runs to prevent water pooling.
• Step 3 – Inspect tubing and ports: Remove and clear tubing, clean inducer port, and ensure tight connections.
• Step 4 – Professional testing: If code 31 persists, a technician should measure draft and pressure switch operation under load.