9 FLASHES
Lennox · SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace
Applies to two-stage (EL296V, SL280V) and modulating (SL297NV) furnaces only. The furnace started in low-stage but when the control called for high-stage, the high-stage pressure switch did not close. Causes: partially blocked vent, weak inducer motor at high speed, or a faulty high-stage pressure switch. Not applicable to single-stage furnaces (ML196E).
Error 9 FLASHES on the Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace means: High-Stage Pressure Switch Did Not Close. The top-ranked community fix is “Test and Replace High-Stage Pressure Switch or Inducer Motor” (hard difficulty, ~60 min, DIY cost: $20-$50). 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.
While many furnace repairs can be done safely at home, consider hiring a qualified technician if:
Average professional repair cost for this issue: $200-$350.
No Previous Fault Code Stored
Blower Motor Calibration Fault
Auxiliary Limit Switch Open
Inducer Motor Fault
Communicating System Fault
System Lockout — Retries Exhausted
Pressure Switch Stuck Closed
Pressure Switch Open — Did Not Close
The Lennox SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace has 8 other known error codes:
Error code 9 FLASHES also appears on 2 other Lennox models:
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