Rheem Error Code d4: Memory card invalid (MEM CARD INVALD) (Furnace)

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rheem error code d4 on a furnace means: Memory card invalid (MEM CARD INVALD). It is also called Rheem diagnostic code d4.

Medium severityFurnaceRGPE/RGLE

Homeowner? What Rheem code d4 means for you

Check, then call Your furnace is reporting: Memory card invalid (MEM CARD INVALD). This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Safe things you can check yourself

Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rheem error code d4 mean?

Memory card missing, corrupt or invalid; furnace runs on network shared data. Shown in standby only (level 1). Manual uses d4 both for 'no card present' and 'card corrupt'.

Applies to: RGPE/RGLE 2-stage 80+

Common causes of Rheem code d4

Memory card removed
Corrupt memory card

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Rheem models that use code d4

RGLE-05(-)BMKR RGLE-07(-)AMKR RGLE-07(-)BRQR RGLE-10(-)BRMR RGLE-12(-)ARMR RGPE-05(-)BMKR RGPE-07(-)AMKR RGPE-07(-)BRQR RGPE-10(-)BRMR RGPE-12(-)ARMR

Other Rheem Furnace codes

Code	Meaning
61	Blower fault - blower not running
66	Blower overspeed (BLOWER OVRSPEED)
68	No blower communication (NO BLWR COMM)
82	Supply air sensor fault (SA SENSOR FLT)
93	Internal control fault
d1	No shared data (NO SHARED DATA)
d5	Card/hardware conflict (CARD-HRD CNFLCT)
d6	Blower HP conflict (BLWR HP CNFLCT)
d7	Blower manufacturer conflict (BLWR MFG CNFLCT)
d8	Old shared data (OLD SHARED DATA)
Flame LED off	No flame sensed (troubleshooting aid)
Flame LED rapid blink	Amber flame LED - unexpected flame

All Rheem Furnace error codes →

Rheem code d4: homeowner questions

What does Rheem code d4 mean?

Memory card invalid (MEM CARD INVALD). Memory card missing, corrupt or invalid; furnace runs on network shared data. Shown in standby only (level 1). Manual uses d4 both for 'no card present' and 'card corrupt'.

Is it safe to keep using my furnace with code d4?

It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.

Can I reset Rheem code d4 myself?

You can try one reset (power off for 30 seconds, then on). If Rheem code d4 comes back, the cause is still there and a licensed technician should check it.

Who can fix Rheem code d4 near me?

Aurora Star Tech Inc. repairs Rheem furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean

Troubleshooting guides

Blowing cold air All brands · Furnace
No heat All brands · Furnace
Short cycling All brands · Furnace
Blower does not start after burners light Rheem · Furnace
Burners go out before the heat call ends / short cycling Rheem · Furnace
Communicating system not found / no communication Rheem · Furnace
ECM blower does not start on heat Rheem · Furnace
Furnace no heat - sequence troubleshooting Rheem · Furnace
Furnace short cycles or does not hold setpoint Rheem · Furnace
Gas valve does not shut off when heat call ends Rheem · Furnace
Indoor blower does not start after burners light Rheem · Furnace
Inducer (draft motor) does not start on heat call Rheem · Furnace
Inducer does not run / does not run on low speed Rheem · Furnace
Inducer runs 60 s then shuts off for 5 minutes, or runs continuously Rheem · Furnace
Inducer runs 60 seconds then off for 5 minutes Rheem · Furnace
No heat - inducer (IDM) does not start Rheem · Furnace
No heat - POWER LED off Rheem · Furnace
Read target airflow from the CFM LED Rheem · Furnace
Thermostat does not hold room temperature Rheem · Furnace

Source: RGPE/RGLE: Table 16 p.49 / Table 20; memory card rules p.38-39. Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.