How to Read Rheem Furnace Error Codes and How to Fix it

This Rheem error codes guide is made for the person who might want to try and fix their furnace. I wanted to list the Rheem furnace error codes with some guidance on what the possible underlying issues could be to make these errors appear.

Rheem furnaces are designed with an advanced 7-segment diagnostic display. They don’t use flashing LED light sequences to indicate errors, like other brands. Rheem and York give you a simple error code that you can use for diagnostics of your furnace problems.

Rheem Furnace Error Codes

There have been many times I have seen furnace error present itself, but the cause of this error is not necessarily what it shows. I will try and give you the best possible diagnosis and a description of what you can do to fix the error.

Here, we will list the meaning of specific Rheem furnace error codes.

Rheem Furnace Normal Operation Codes

cY1 on (Legacy Mode Only)
CY2 or Any Communicating Cooling Call
dFDefrost active
FContinuous fan
H flashingFurnace Calibration
HFurnace Heat
hGas heat – No “V” Signal (Legacy Mode Only
h flashingCalibration – No “V Signal (Legacy Mode Only
cd or CdDehumidification active (Legacy Mode Only)

Rheem Furnace Shared Data Error

d1No Shared Data
d3Airflow Mismatch
d4Memor Card Invalid
d5Card-Hardware Conflict
d6Blower Horsepower Conflic
d7Blower Manufacturer Conflict
d8Old Shared Data

Rheem Furnace Flame Sense Signal Error Codes

10One Hour Lockout
11Failed Ignition
12Low Flame Sense
13Flame Lost
14Unexpected Flame

Rheem Furnace Limit Control Error Codes

22Main Limit Open
23Heat Assist Limit (HALC) Open
33Manual Reset Limt (MRLC) Open

Rheem Furnace Pressure Switch Error Codes

44Low Pressure Switch Closed – Inducer OFF
45Low Pressure Switch Open – Inducer on High
46Low Pressure Switch Open – Inducer on Low
55High Pressure Switch Closed – Inducer OFF
57High Pressure Switch Open

Rheem Furnace Blower Error Codes

60Blower Fault – Blower Remains Running
61Blower Fault – Blower Not Running
66Blower Overspeed Fault
68No Communications with Blower Motor

Rheem Furnace Gas Valve Error Codes

77No Communications with Gas Valve
78Gas Valve Servo Fault

Another Misc. Error Codes

26Line and Neutral Reversed
82Supply Air Temp / Sensor Fault
93Internal Fault / Control Fault

Common Problems and Possible Solution

This chapter summarizes the most common problems you could encounter with your Rheem furnace. If you are unable to diagnose and solve the problem with the information below, contact an experienced and certified HVAC technician for certain complex problems.

ProblemsPossible Solutions
Flame Sensor ProblemIf the flame sensor is dirty, clean the sensor. If faulty or broken, replace the flame sensor. Click Here for the detailed guide to clean/replace furnace flame sensor.
Circuit Breaker/FuseTry resetting your furnace’s circuit breaker. Click Here for the detailed guide tp reset your furnace.
IgniterCheck the furnace igniter for cracks, if it is then replace the igniter. If it isn’t cracked, use a multimeter to test for continuity. Click Here for the detailed guide to check the furnace igniter.
Blower MotorCheck the blower motor. If it isn’t running, the motor has likely broken. If the motor runs but air doesn’t move, the connecting belt may the problem. Click Here for the detailed blower motor troubleshooting guide.
Internal FaultCheck the furnace control board. Click Here for the detailed guide to troubleshooting funace control board.

Many modern furnaces have an LED light that will either be flashing or just showing some codes. Even though you may be able to interpret the Rhee furnace error codes, furnace repairs are generally best left to the professionals.

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About Mas Broto

Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.