Coleman Furnace 3 Green Flashes (CP9C Echelon Modulating)
StatusShown as: Three green flashes after holding the LAST ERROR button more than five seconds
Indicator for 'Error codes cleared from memory'. Not a fault.
Manual wording: “Three Green Flashes - Indicator for "Error codes cleared from memory".”
Documented for: CP9C Echelon modulating furnaces
Likely causes, most common first
- The stored fault history was cleared with the LAST ERROR button
When to call a technician
Not a fault, but clearing the history erases what a technician needs to chase an intermittent problem - leave it alone before a service visit.
A Coleman furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Installation Manual - Residential Gas Furnace with ECM Motor, Models TP9C*C, YP9C*C, CP9C*C, LP9C*C (Up to 98% Modulating Multi-position), 681292-UIM-B-1211 (Johnson Controls Unitary Products (Coleman), CP9C*C Coleman Echelon modulating gas furnace (manual also covers the identical TP9C, YP9C and LP9C chassis)) · checked 2026-08-25