Rheem · Furnace / HVAC
1 blink Soft lockout
What this code means
The furnace failed to light but will automatically retry after a short cool-down period rather than fully locking out.
Most likely causes
- Temporary ignition hiccup
- Marginal gas pressure
- Dirty flame sensor
What to try first
Let the furnace attempt its automatic retry; if it keeps recurring, clean the flame sensor.
Good news: this one is often fixable without a service call. If it persists after the steps above, have it looked at.
FAQ
What does Rheem error code 1 blink mean?
Soft lockout. The furnace failed to light but will automatically retry after a short cool-down period rather than fully locking out.
Can I fix Rheem code 1 blink myself?
Often, yes. Let the furnace attempt its automatic retry; if it keeps recurring, clean the flame sensor.
What causes Rheem code 1 blink?
The most common causes are: temporary ignition hiccup; marginal gas pressure; dirty flame sensor.
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.