Rheem Furnace Error Codes: Full List & Meanings

Every Rheem furnace error code we have verified against Rheem's own support pages, with its official meaning. This list covers standard gas furnaces (not modulating, lxe or two-stage). Codes vary by model, so confirm in your owner's manual. Support: Rheem dealer (rheem.com).

Smell gas? Leave the building now. Do not touch light switches, phones or appliances inside. Call your gas utility or 911 from outside. CO alarm sounding or headache, dizziness or nausea? Get everyone outside and call 911. Gas valves, burners, venting and wiring are for a licensed technician only. See our safety policy.

Codes by system

Heating

Venting / airflow

All Rheem furnace error codes

Codes marked "Reset only" or "Service" have no separate page because the manufacturer publishes no owner fix beyond a reset or a service call.

Code	Official meaning	System	Owner action
3 blinks	The limit switch is open: overheating, usually from restricted airflow.	Heating	Owner checks
2 blinks	The pressure switch stays open. Venting or the inducer can cause it.	Venting / airflow	Owner checks
1 blink	The furnace is in a 1-hour soft lockout after failed ignition attempts.	Heating	Owner checks
4 blinks	The manufacturer lists 4 blinks as: pressure switch failure (remains closed). A licensed HVAC technician must diagnose this.	Control / electronics	Service
5 blinks	The manufacturer lists 5 blinks as: twinning circuit failure (twinning boards only; can occur with some electronic thermostats). A licensed HVAC technician must diagnose this.	Control / electronics	Service

Symptoms

Sources

https://my.rheem.com/pts/Topics/GF_Flash_Code.asp (official)

Last reviewed: October 20, 2026. ErrorCodePro is not affiliated with Rheem.