Rheem Furnace Code 58
Soft lockout
Water circuit open. The control cannot see continuity between pins 1 and 2 of connector P4, which is how it verifies both collector-box water sensors are present and wired. Gas heat is blocked; cooling still runs.
Manual wording: “WATER CIRCUIT OPEN ... The IFC cannot detect electrical continuity between pins 1 and 2 of connector P4 of the furnace control.”
Documented for: (-)97V, (-)96V condensing furnaces
Likely causes, most common first
- Wiring has been damaged between the control or sensor
- Connection of P4 at the IFC or at the water sensors is not properly made
- Water sensor has been removed
When to call a technician
The water sensors and their wiring are inside the furnace - a technician needs to repair the connection or replace a missing sensor.
A Rheem furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Instructions for Upflow Condensing Modulating, Communicating Gas Furnaces - (-)97V Series (92-24161-126-04) (Rheem Manufacturing Company, R97V series modulating condensing gas furnace (and R98V); TABLE 18 normal operation codes, TABLE 19 fault codes, pages 94-104) · checked 2026-08-25
- Installation Instructions for 4 Position Condensing Two-Stage, Communicating Gas Furnaces - (-)96V Series (92-24161-124-08) (Rheem Manufacturing Company, R96V series and (-)(-)96MDV two-stage condensing gas furnaces; TABLE 19 normal operation codes, TABLE 20 fault codes, pages 111-120) · checked 2026-08-25