Question 1

What does Rheem error code 5 flashes mean?

Accepted Answer

Five flashes on a Rheem furnace indicates flame rollout has been detected. This is a serious safety condition that can be caused by a cracked heat exchanger, blocked flue, or severely blocked return air. Inspect the heat exchanger carefully for cracks. Never bypass the rollout switch as this is a critical safety device.

Question 2

What does Rheem error code 8 flashes mean?

Accepted Answer

Eight flashes on a Rheem furnace means ignition failure with no flame established. Check the hot surface igniter for cracks or open circuit, verify the gas supply is on and at correct pressure, and clean the flame sensor with emery cloth.

Question 3

How do I reset a Rheem furnace lockout?

Accepted Answer

To reset a Rheem furnace showing 1 flash (system lockout), turn off power at the breaker for 30 seconds. Before resetting, diagnose the ignition issue: check the igniter, gas supply, and flame sensor. Repeated lockouts without fixing the root cause can damage the ignition system.

Question 4

Are Rheem and Ruud error codes the same?

Accepted Answer

Yes. Rheem and Ruud are manufactured by the same company (Rheem Manufacturing). They share identical control boards and LED flash code systems, so all error codes listed here apply to both Rheem and Ruud equipment.

Code	Description	Common Cause	Fix
1 flash	System lockout	Multiple ignition failures	Power cycle to reset, diagnose ignition issue
2 flashes	Low pressure / suction pressure fault	Low refrigerant, low pressure switch open, or restricted filter drier	Check refrigerant charge, inspect low pressure switch, check for restrictions
3 flashes	High pressure switch open	Dirty condenser coil, failed condenser fan, overcharge, or non-condensables	Clean condenser coil, check condenser fan motor and cap, check charge, check for air in system
4 flashes	High temperature limit open	Low airflow or dirty filter	Replace filter, check blower
5 flashes	Flame rollout detected	Cracked heat exchanger, blocked flue, or blocked return air	Inspect heat exchanger for cracks, check flue pipe. SAFETY: Do not bypass rollout switch
6 flashes	Pressure switch stuck closed	Welded contacts	Replace pressure switch
7 flashes	Pressure switch stuck open	Inducer failure or blocked drain	Check inducer motor, clear condensate drain
8 flashes	Ignition failure / no flame	Failed igniter, no gas, or weak flame signal	Check igniter, verify gas supply, clean flame sensor
9 flashes	Ground fault detected	Short to ground in wiring or water damage to board	Inspect all wiring for damage, check board for water/corrosion

Rheem Error Codes & Fault Codes

Detailed Code Reference

Frequently Asked Questions

What does Rheem error code 5 flashes mean?

What does Rheem error code 8 flashes mean?

How do I reset a Rheem furnace lockout?

Are Rheem and Ruud error codes the same?

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