Lennox E228

What does Lennox E228 mean?

E228 indicates the combustion air inducer failed to complete its automatic pressure switch calibration sequence. The SL280DFNV IFC runs a calibration routine at startup to map inducer speed to draft pressure for each pressure switch; if the measured pressure does not match the expected profile within the allowed time, the board logs E228. This typically points to a vent restriction, a failed pressure switch, or an inducer motor that cannot reach calibration speed.

Symptoms

• E228 displayed at startup — furnace does not proceed to the ignition trial.
• Inducer motor runs during calibration attempt but heating sequence aborts.
• Alert may be accompanied by E276 if calibration retries are exhausted.
• No heat produced; fan runs in post-purge and then system waits before retrying.

Common causes

• Blocked exhaust or intake vent pipe preventing the inducer from producing calibration draft levels.
• Cracked or disconnected pressure switch hose causing incorrect pressure reading during calibration.
• Faulty pressure switch that does not accurately respond to inducer draft during the calibration sweep.
• Weak combustion air inducer motor unable to reach the speed required for calibration.
• Clogged condensate trap or blocked drain impeding draft during calibration.

Diagnostic steps

1. 01

   Inspect all vent pipes and terminations

   Check both intake and exhaust PVC pipes for ice, debris, collapsed sections, or incorrect slope. Clear any restriction and verify termination clearances meet the SL280DFNV IOM requirements.

2. 02

   Clear the condensate trap and drain

   Flush the condensate trap and verify free drain flow. A sluggish drain can back water into the inducer housing and affect draft during the calibration sweep.

3. 03

   Inspect pressure switch hoses

   Check all hoses between the inducer housing and pressure switches for cracks, disconnection, or water blockage. Replace any damaged hose and clear any trapped water.

4. 04

   Check pressure switch wiring connections

   Verify all pressure switch electrical connections are secure at both the switch terminals and the IFC board. A loose connection can cause intermittent signal dropout during calibration.

5. 05

   Measure inducer draft during calibration attempt

   Connect a manometer to the inducer housing tap and observe pressure during the calibration sweep. Compare against expected calibration levels in the SL280DFNV IOM service section.

When to call a professional

If draft pressure is below calibration spec with a clear vent system, the inducer motor or capacitor is degrading. E228 also requires pressure switch calibration verification using a manometer — a licensed technician has the proper tools to measure inducer performance at each calibration speed step and determine whether the inducer, pressure switch, or IFC board is the root cause.