Rheem · Furnace

d4 Memory card invalid (MEM CARD INVALD)

Medium severity RGPE/RGLE

What the control is telling you

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+

Likely causes

Memory card removed
Corrupt memory card

Test and repair steps

Check whether the original memory card is attached to the IFC or inserted in connector J15.
If the IFC was replaced, break the original memory card off the old control and insert it in J15 of the new one.
Warning: Never swap memory cards or controls between furnaces or from a condenser/air handler - wrong data can cut heating airflow and trip the main limit.
If the original card is lost, order the correct replacement memory card for this model from ProStock and insert it in J15.
Communicating systems confirm the model in the furnace user menu under Unit Info matches the rating label.

Settings for these units

Filter sizes as shipped, upflow (Table 19) · RGPE/RGLE
Reduced clearance to combustibles (Fig. 3 and 4) · RGPE/RGLE

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Source: RGPE/RGLE: Table 16 p.49 / Table 20; memory card rules p.38-39. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.