Error code reference

Lennox Furnace Error Code 3 Flashes

Pressure switch open with combustion air inducer energized (Control 103085).

SourceLennox ML195DF Series - Service Manual: High-Efficiency Gas FurnacesPage 9, Table 6

Diagnostic procedure

The full 3 Flashes procedure

Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Check intake/exhaust vents for blockage; check pressure switch hoses and connections.

SourceLennox ML195DF Series - Service Manual: High-Efficiency Gas FurnacesPage 9, Table 6

Unlock with pass

More steps, wiring diagram references, and verified part numbers

Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.

Unlock 3 Flashes procedure $9.95

Or subscribe: $29/month for all codes plus Max diagnostics, with 70 Max messages a day. Plus applicable tax.

Where this code is documented

4 manuals in the MyPros+ library document this code for Lennox furnace.

Models covered by the manuals that document this code

More models are covered than are listed here.

75,000+ service documents · 20,000+ error codes · 100+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass · Plus applicable tax

The full 3 Flashes procedure

Where this code is documented

Models covered by the manuals that document this code

Related Lennox furnace error codes