Rheem R801SA furnace code 93: Internal control fault
Professional repair
What does code 93 mean on a Rheem R801SA (801S downflow) furnace display? Code 93 is a hard lockout for an internal control fault, which can include abnormal voltage persisting at the gas-valve contacts. Cycling the thermostat heat call does not clear it.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
A technician must verify the gas-valve circuit and control board with live measurements. Because the code can involve abnormal gas-valve voltage, the furnace should stay off until checked.
Possible causes
- Unspecified internal fault detected by the control board TECH
- Persistent abnormal voltage at the gas-valve contacts TECH
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 93 mean on a Rheem R801SA (801S downflow) furnace display?
Code 93 is a hard lockout for an internal control fault, which can include abnormal voltage persisting at the gas-valve contacts. Cycling the thermostat heat call does not clear it.
How do I fix Rheem R801SA furnace code 93?
If there is gas odor or a CO alarm, leave without operating switches and call emergency services from outside. Otherwise keep the furnace off and book service for the control and gas-valve circuit. Do not cycle power to clear the code.
How much does it cost to fix Rheem R801SA furnace code 93?
Expect diagnostic time on the control and gas-valve circuit. If the board is confirmed faulty, cost depends on part availability and fitting labor for this 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.35
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.