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

Code	Meaning
0	Standby
c	Y1 on (Legacy Mode Only)
C	Y2 or Any Communicating Cooling Call
dF	Defrost active
F	Continuous fan
H flashing	Furnace Calibration
H	Furnace Heat
h	Gas heat – No “V” Signal (Legacy Mode Only
h flashing	Calibration – No “V Signal (Legacy Mode Only
cd or Cd	Dehumidification active (Legacy Mode Only)

Rheem Furnace Shared Data Error

Codes	Meaning
d1	No Shared Data
d3	Airflow Mismatch
d4	Memor Card Invalid
d5	Card-Hardware Conflict
d6	Blower Horsepower Conflic
d7	Blower Manufacturer Conflict
d8	Old Shared Data

Rheem Furnace Flame Sense Signal Error Codes

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

Rheem Furnace Limit Control Error Codes

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

Rheem Furnace Pressure Switch Error Codes

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

Rheem Furnace Blower Error Codes

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

Rheem Furnace Gas Valve Error Codes

Codes	Problems
77	No Communications with Gas Valve
78	Gas Valve Servo Fault

Another Misc. Error Codes

Codes	Problems
26	Line and Neutral Reversed
82	Supply Air Temp / Sensor Fault
93	Internal 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.

Problems	Possible Solutions
Flame Sensor Problem	If 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/Fuse	Try resetting your furnace’s circuit breaker. Click Here for the detailed guide tp reset your furnace.
Igniter	Check 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 Motor	Check 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 Fault	Check 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.