Rheem · Furnace / HVAC
5 blinks Twinning circuit failure
What this code means
Specific to Rheem systems configured with two furnaces working together (twinning) — the communication circuit between them has failed.
Most likely causes
- Wiring fault between the twinned units
- Failed twinning module on one furnace
What to try first
Only relevant if you have a twinned system; this needs a technician familiar with the twinning configuration.
Safety note: if this code returns after one clean reset, stop resetting it — repeated lockouts usually mean a real fault that needs a licensed technician. Never bypass a safety switch.
FAQ
What does Rheem error code 5 blinks mean?
Twinning circuit failure. Specific to Rheem systems configured with two furnaces working together (twinning) — the communication circuit between them has failed.
Can I fix Rheem code 5 blinks myself?
Usually not. Only relevant if you have a twinned system; this needs a technician familiar with the twinning configuration. If the code returns after one reset, it needs a licensed technician.
What causes Rheem code 5 blinks?
The most common causes are: wiring fault between the twinned units; failed twinning module on one furnace.
Other Rheem furnace codes
All Rheem furnace error codes →
Other furnace brands: Trane · Carrier · Lennox · Goodman · Amana · American Standard · Bryant · Generic · Nest
This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.