6 FLASH
Rheem · Rheem R96V 96% AFUE Two-Stage Variable Speed Upflow Gas Furnace
The IFC board has detected that the 115VAC line voltage has reversed polarity (hot and neutral wires swapped) or there is no proper earth ground connection. Rheem furnaces require correct polarity for the flame sensing circuit to function — the flame sensor works by using the flame as a conductor between the sensor rod and the grounded burner. If polarity is reversed or ground is missing, flame sensing fails. Check wiring at the furnace disconnect switch, circuit breaker panel, and any junction boxes. Use a multimeter or plug-in outlet tester to verify correct hot, neutral, and ground connections.
Error 6 FLASH on the Rheem Rheem R96V 96% AFUE Two-Stage Variable Speed Upflow Gas Furnace means: Power Reversed or No Ground. The top-ranked community fix is “Inspect and Repair Furnace Wiring and Ground Connections” (medium difficulty, ~45 min, DIY cost: $5-$15). 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: $120-$180.
Normal — Heat Call Active
Rollout Switch Open
High-Stage Pressure Switch Open (Two-Stage Only)
System Lockout — Ignition Failed
Pressure Switch Stuck Closed
Pressure Switch Stuck Open
Flame Sensed Without Gas Valve Command
Low Flame Signal
The Rheem Rheem R96V 96% AFUE Two-Stage Variable Speed Upflow Gas Furnace has 8 other known error codes:
Error code 6 FLASH also appears on 1 other Rheem model:
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