TL;DR: The short letter codes on a Jenn-Air refrigerator display are not all faults. Some are reminders, such as WF for the water filter or PO for a power outage. Some are alerts, such as DI for a door left open. Others report a sensor, fan or board problem, such as RS, EF or SY-CE. This glossary groups the Jenn-Air refrigerator display messages we document by what they mean and what to do, so you can tell a reminder from a repair.
Which messages are reminders and not faults?
Start here, because these are the ones that are usually harmless. WF is a routine reminder that the water filter cartridge has reached its usage limit; replacing the cartridge and resetting the reminder as the manual describes clears it. PO simply reports that the refrigerator recently lost power and got it back. Nothing is broken; the unit is telling you it noticed. PF is similar but carries a warning: a power interruption was recorded, and you should check on the safety of the food, especially in the freezer, before you trust it.
All three reflect events, not failures. If PO or PF keeps appearing without any outage you can account for, look at the household supply, a loose plug or a tripping breaker, because the refrigerator is only reporting what it sees.
A practical rule for PF: if the freezer food still has ice crystals and feels hard, it stayed frozen; if it has softened or the refrigerator side is warm to the touch, use a thermometer and apply the usual food-safety judgment before eating anything that sat above 40 degrees Fahrenheit for long. When in doubt, throw it out, and let the unit run for a few hours to stabilize before you restock it.
Which messages are about the door?
Two codes concern the door, and they are easy to confuse. DI is the ajar alarm: a door has stood open long enough that the refrigerator beeps or displays the message. Closing the door usually ends it. dE is different. It says a door is not registering as fully closed even though you may think it is, and the cause is an obstruction, a misaligned door or a worn seal. Check that bins are pushed in, nothing is propping the door, and the gasket is clean and soft. Our guide to the refrigerator door seal covers the test.
Which messages are about sensors?
RS says the thermistor that reads fresh-food temperature has drifted or failed, so the control board cannot regulate cooling accurately. HS concerns the sensor that tracks fresh-food humidity for the crisper drawers, and it is not reading correctly. Sensor messages call for diagnosis, not a reset: the board is working with bad information, and the temperature may drift higher or lower than the setting. If you see RS, put a thermometer in the fresh-food compartment to check the real temperature while you wait for service.

Which messages are about fans and cooling?
These are the codes that matter most for the food in the refrigerator, because they describe how cold air is made and moved:
Pages exist for CF, EF, FF, DF and PC. A fan code usually comes with a refrigerator that is warm in one section and cold in another, or one that runs constantly. A DF code leaves a wall of frost behind the freezer panel. Those are service calls: the parts are inside the cabinet, near the evaporator and the sealed system. The model-specific story for one family is in our JFFCC72 running too cold guide.
What do the system and ice messages mean?
SY-CE means internal boards inside the refrigerator have lost the ability to talk to each other, a communication fault that sits above any single part. IC points at the built-in ice maker module, which has stalled mid-cycle or has a sensor problem that stops ice production. Treat both as technician items; a power reset can sometimes bring a stalled module back for a while, but it is not a repair.
How do you use this glossary?
Keep the list handy near the refrigerator, or save a photo of the table on your phone, so you can match a message in seconds when it appears at night. Match the message, then ask three questions: Is it a reminder, an alert or a fault? Did anything change in the house, such as an outage, a new filter or a door left open? Is the food still cold? If the answers point to a fault, note the exact message and when it appeared, and our Jenn-Air refrigerator repair technicians can take it from there. For the broader vocabulary, our error codes glossary and refrigeration terms glossary fill in the rest. You can book a visit whenever a message will not clear.