MEDIUM URGENCY

Lennox E155 - Inducer Speed Fault

E155

Inducer motor speed out of expected range.

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

What This Code Means

Error code E155 on Lennox iComfort communicating systems means the inducer motor speed is outside the normal operating range. Variable-speed ECM inducer fault or control communication issue.

Likely Causes (Ranked)

Most common

Failed ECM inducer module

What: Inducer motor's variable-speed electronics have failed.

How to check: Tech tests inducer module.

Fix: Replace inducer assembly.

Shop parts

Common

Restricted exhaust vent

What: Blockage forces inducer to run outside normal speed range.

How to check: Inspect outdoor exhaust outlet.

Fix: Clear blockage.

Shop parts

Common

Communication harness fault

What: Loose or damaged wiring between control and inducer.

How to check: Inspect connectors.

Fix: Reseat or replace harness.

Diagnostic Steps

Cut power
Inspect exhaust vent for blockage
Check inducer wiring
Replace inducer if persistent
Call HVAC tech

Frequently Asked Questions

Same on Armstrong/Ducane?

Yes - all Lennox-family iComfort systems share codes.

Cost to replace inducer?

$200-400 part plus labor.

DIY?

Moderate difficulty - 2-3 hours.

Related Lennox Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Lennox parts.

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