Goodman furnace d4: Invalid memory card data
d4 means the control cannot read valid configuration from the memory card that tells it what furnace it is installed in. Without that, it does not know how to run the equipment.
Applies to: Goodman GMVC96, GMVM97, GCVC96, GCVM97 and Amana AMVC96, AMVM97 series communicating gas furnaces with a two-character display.
What it means
Some communicating furnace controls take their model-specific configuration from a memory card rather than having it built in, which is what allows one board design to serve several models. The card holds the airflow tables, staging behaviour, and operating parameters for the particular furnace. d4 means the control read the card and got data it could not use. Because the configuration determines how the furnace operates, the control cannot safely proceed without it. This is essentially always a service-related fault — a card missing, not seated, damaged, or from a different model.
Most common causes
- The memory card is not fitted, or is not fully seated in its socket.
- The card is damaged, or its contacts are dirty or corroded.
- A card from a different furnace model fitted during a repair.
- A replacement control board supplied without the card being transferred from the old one.
- Card data corrupted by a power event.
- A failed card socket on the control board.
How to diagnose it
- Establish what work has been done recently. This code following a control board replacement is the overwhelmingly likely story — the card is meant to be transferred and sometimes is not.
- Have the furnace model number from the rating plate available, since the correct card is model-specific.
- Note whether the fault followed a power cut or a surge, which can corrupt the data.
- Note that the furnace will not run properly in this state; it is not a cosmetic fault.
How to fix it
- This is technician work. The card sits on the control board inside the cabinet.
- If a control board was recently replaced, contact whoever did the work — the card should have been transferred or a correct replacement supplied.
- The fix is to fit the correct card for the model, seat it properly, and clean the contacts if corroded.
- Do not accept a card from a different model as a workaround. The configuration determines airflow and staging, and wrong values produce overheating or poor performance.
Notes
The memory card is easy to overlook during a board swap and expensive to overlook in consequences. If a control board is ever replaced on one of these furnaces, it is worth confirming with the technician that the card was transferred.