Lennox EL296UHV Error Code Soft Lockout - Pressure Switch Failure During Retry: Soft Lockout - Pressure Switch Failure During Retry

What Does Code Soft Lockout - Pressure Switch Failure During Retry Mean?

Error code E271 on the Lennox IFC control board indicates a soft lockout caused by a pressure switch remaining open. This is the escalation of the individual pressure switch fault codes (E223, E225, E227) — the furnace tried to start multiple times, and each time the pressure switch failed to close or opened during operation. After exhausting its retry count, the board enters soft lockout.

Soft lockout means the furnace will automatically attempt to restart after a timeout period (typically one hour on Lennox IFC boards). However, if the underlying cause isn't corrected, the furnace will fail again and re-enter lockout. This cycle will continue indefinitely until the problem is fixed or a technician intervenes.

The root cause is the same as the underlying pressure switch code: blocked exhaust vent or combustion air intake, clogged condensate drain (on high-efficiency models), cracked or disconnected pressure switch hose, or a failing inducer motor. Because E271 represents multiple failed attempts, the blockage or fault is likely consistent rather than intermittent. Checking the venting system for obstructions is the first and most effective DIY step.

How to Fix It: Check Exhaust Vent and Combustion Air Intake

What You'll Need

• Flashlight
• Step ladder (if vent terminations are above ground level)
• Mirror or phone camera (to look inside vent pipes)

Steps

1. Turn off power AND shut off gas supply Switch the furnace power off at the disconnect switch near the unit AND at the circuit breaker. Locate the gas shutoff valve on the gas line leading to the furnace and turn it to the OFF position (perpendicular to the pipe). If you smell gas at any point, leave the area immediately and call your gas company from outside.
2. Inspect the exhaust vent and intake pipe terminations Find where the exhaust vent and combustion air intake pipes exit your home. On high-efficiency Lennox furnaces (SLP98, EL296), these are PVC/CPVC pipes exiting through a side wall. Check both openings for blockages — bird nests, wasp nests, ice/snow buildup, leaves, or debris. Remove any obstructions. Because E271 is a lockout from repeated failures, the blockage is likely substantial.
3. Check the full vent pipe run Trace the vent pipes from the furnace to the exterior. Check all joints for disconnection or damage. Look for sagging sections or areas where debris could have accumulated. On standard-efficiency models with metal flue pipes, check for rust holes or collapsed sections.
4. Check the condensate drain and trap (high-efficiency models) On 90%+ AFUE Lennox furnaces, check the condensate drain line and trap for blockages. A fully clogged drain will cause water to fill the inducer housing, completely preventing proper pressure switch operation. Clear any blockages and verify the drain flows freely.
5. Inspect the pressure switch hose(s) Inside the furnace, check the rubber hose(s) from the inducer to the pressure switch(es). A disconnected or severely cracked hose will prevent the pressure switch from ever closing. Reconnect or note for replacement if damaged.
6. Restore power and test Replace the access panel. Turn the gas supply back on (valve handle parallel to the pipe). Restore power at the disconnect switch and breaker. Cycling the power clears the soft lockout. Set your thermostat to call for heat and observe the startup sequence. The inducer should start, the pressure switch should close, and ignition should follow.

When to Call a Professional

Contact a licensed HVAC technician if:

• The exhaust vent and intake are clear but E271 keeps recurring after power cycling
• The inducer motor does not start or sounds extremely weak
• The pressure switch hose is damaged and needs replacement
• There is a significant condensate leak from the furnace
• You notice a gas smell at any point during the process