Rheem R801SA furnace code 55: Pressure switch closed
Professional repair
What does code 55 mean on a Rheem R801SA (801S downflow) furnace display? Code 55 means the pressure switch circuit reads closed when the control expects it open. The contacts must be open before the next heating cycle can begin.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
A technician checks the pressure switch, its wiring and its connection to the control to find why the circuit reads closed. The code does not by itself prove the switch is faulty.
Parts for this code
No model-verified part number is listed here. Have the fault diagnosed and the correct part matched to your furnace before ordering.
Questions about this code
What does code 55 mean on a Rheem R801SA (801S downflow) furnace display?
Code 55 means the pressure switch circuit reads closed when the control expects it open. The contacts must be open before the next heating cycle can begin.
How do I fix Rheem R801SA furnace code 55?
Book service with the code recorded. The technician confirms whether the switch contacts, wiring or the control reading is at fault before replacing anything. Never jumper or disconnect the pressure switch to force a heating cycle.
How much does it cost to fix Rheem R801SA furnace code 55?
Testing the pressure-switch circuit determines whether the work involves the switch, wiring or control. Each repair requires different labor; the code cannot choose between them.
Related symptoms
These symptoms can appear alongside this code. The link is an association, not a diagnosis, and code meanings vary by brand, model and control.
Applies to
R801SA / 801S downflow single-stage 80% furnace with PSC motor
Different Rheem generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Installation Instructions for Downflow Single Stage Gas Furnaces, p.34
Verified against Rheem 801S Series Installation Instructions — OEM143-14 mirror, p.34
Verified against Rheem 801S Series Installation Instructions — OEM143-14 mirror, p.43
Last verified 2026-10-07 · page updated 2026-10-07 · how we verify
Related Rheem furnace codes
These codes use the same rheem 801s downflow single-stage control (manual 92-24161-143-14) system.