MEDIUM URGENCY

Lennox E227 - Pressure Switch Calibration Error

E227

Pressure switch calibration error - unable to verify proper operation.

Brand: Lennox (Also covers Armstrong Air, Aire-Flo, Ducane) | Equipment: Gas Furnace

What This Code Means

Error code E227 on Lennox iComfort means the system was unable to perform pressure switch calibration during startup. Usually points to a vent restriction or failing pressure switch.

Likely Causes (Ranked)

Most common

Restricted vent system

What: Partial blockage prevents normal pressure switch operation.

How to check: Inspect intake and exhaust outlets.

Fix: Clear blockages.

Shop parts

Common on 90%+ AFUE

Plugged condensate trap

What: Sediment buildup affects pressure readings.

How to check: Inspect condensate trap.

Fix: Clean trap and drain line.

Common

Failing pressure switch

What: Switch operates intermittently or outside calibration tolerance.

How to check: Tech manometer test.

Fix: Replace switch.

Shop parts

Diagnostic Steps

Inspect intake and exhaust outlets
Clean condensate trap
Check pressure switch wiring
Replace switch if persistent

Frequently Asked Questions

Difference between Lennox E223 and E227?

E223 = pressure switch failed open. E227 = calibration drift, switch operating but values off.

Same on Armstrong/Ducane?

Yes - shared iComfort system.

DIY?

Vent and trap inspection yes; switch replacement straightforward.

Related Lennox Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Lennox parts.

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