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11 FLASHES

Lennox · SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace

Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace 11 FLASHES Error Fix: Auxiliary Limit Switch Open

An auxiliary or secondary limit switch in the safety circuit has tripped. Some Lennox furnaces have multiple limit switches. Same troubleshooting as 7 FLASHES: check airflow, filter, blower operation. On some models, this code indicates the vent limit switch has tripped, suggesting the vent system is partially blocked.

High severity2 fixes available

Quick Answer

Error 11 FLASHES on the Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace means: Auxiliary Limit Switch Open. The top-ranked community fix is “Inspect and Replace Auxiliary Limit Switch or Vent System Cleaning” (hard difficulty, ~60 min, DIY cost: $5-$20). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · furnace

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many furnace repairs can be done safely at home, consider hiring a qualified technician if:

This is a high severity error — continued use may cause damage or a safety hazard
The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $150-$300.

Other Lennox Models with Error 11 FLASHES

EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace

furnace · 2 fixes

ML196E Merit Series 96% AFUE Single-Stage Gas Furnace

furnace · 2 fixes

SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace

furnace · 2 fixes

Other Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace Error Codes

1 FLASH

No Previous Fault Code Stored

2 fixes

10 FLASHES

Blower Motor Calibration Fault

Inducer Motor Fault

Communicating System Fault

2 fixes

2 FLASHES

System Lockout — Retries Exhausted

2 fixes

3 FLASHES

Pressure Switch Stuck Closed

2 fixes

4 FLASHES

Pressure Switch Open — Did Not Close

2 fixes

5 FLASHES

Flame Sensed Without Call for Heat

2 fixes

People Also Ask About Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace Error 11 FLASHES

What does error code 11 FLASHES mean on a Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace?

Error code 11 FLASHES on the Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace means: Auxiliary Limit Switch Open. An auxiliary or secondary limit switch in the safety circuit has tripped. Some Lennox furnaces have multiple limit switches. Same troubleshooting as 7 FLASHES: check airflow, filter, blower operation. On some models, this code indicates the vent limit switch has tripped, suggesting the vent system is partially blocked.

How do I fix error code 11 FLASHES on my Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace?

The most successful fix is "Inspect and Replace Auxiliary Limit Switch or Vent System Cleaning" (hard difficulty, ~60 minutes). Estimated DIY cost: $5-$20. HomeMD has 2 community-ranked fixes for this error.

Is error code 11 FLASHES on a Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace serious?

This error is rated high severity. You should address it promptly — continued use could cause damage or safety concerns.

Can I fix Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace error 11 FLASHES myself?

Yes — the top-ranked community fix ("Inspect and Replace Auxiliary Limit Switch or Vent System Cleaning") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Multimeter, Vent cleaning brush, Flashlight.

How much does it cost to repair Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace error 11 FLASHES?

DIY cost: $5-$20. Professional repair typically costs $150-$300. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace have?

The Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace has 8 other known error codes, including: 1 FLASH (No Previous Fault Code Stored), 10 FLASHES (Blower Motor Calibration Fault), 12 FLASHES (Inducer Motor Fault), 13 FLASHES (Communicating System Fault), 2 FLASHES (System Lockout — Retries Exhausted), and 3 more.

Which other Lennox models have the 11 FLASHES error?

Error code 11 FLASHES also appears on 3 other Lennox models: EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace, ML196E Merit Series 96% AFUE Single-Stage Gas Furnace, SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace have?

The Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace has 8 other known error codes:

1 FLASH — No Previous Fault Code Stored (2 fixes)
10 FLASHES — Blower Motor Calibration Fault (2 fixes)
12 FLASHES — Inducer Motor Fault (2 fixes)
13 FLASHES — Communicating System Fault (2 fixes)
2 FLASHES — System Lockout — Retries Exhausted (2 fixes)
3 FLASHES — Pressure Switch Stuck Closed (2 fixes)
4 FLASHES — Pressure Switch Open — Did Not Close (2 fixes)
5 FLASHES — Flame Sensed Without Call for Heat (2 fixes)

Which other Lennox models have the 11 FLASHES error?

Error code 11 FLASHES also appears on 3 other Lennox models:

EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace (furnace) · 2 fixes
ML196E Merit Series 96% AFUE Single-Stage Gas Furnace (furnace) · 2 fixes
SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace (furnace) · 2 fixes

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