Frigidaire Refrigerator OP — Open Freezer or Fresh-Food Thermistor

What this code means

The control detects an open circuit in either the freezer (FZ) or fresh-food (FF) temperature-sensor circuit. The display position identifies which compartment is affected.

Applicability

Applies to Frigidaire and Electrolux-group refrigerators displaying OP. Which compartment is affected is shown by where the code appears — the freezer display for the freezer thermistor, the fresh-food display for the fresh-food one. OP and SH are opposite halves of the same test: OP is an open circuit, SH a shorted one.

Symptoms

• One compartment drifts off temperature while the other stays correct
• The compressor either runs almost continuously or barely runs at all, because the control has lost the reading it regulates from
• The code may clear on its own and return, particularly after the door has been opened and closed repeatedly

Most likely causes

• A thermistor has failed open
• A sensor connector is unplugged or corroded
• A wire is broken, pinched or backed out of a connector
• The main control input circuit is damaged

Diagnostic logic

OP means the control is seeing an open circuit — infinite resistance — where it expects a thermistor. That is a more specific clue than a general 'sensor fault', because a thermistor that has drifted or aged usually reads a wrong value rather than no value at all. An open circuit points first at a broken connection and only then at the sensor: the connector at the control board, and the section of harness that flexes every time the door or a mullion moves, are the places to look before ordering a part. The intermittent pattern is the tell — a fault that comes and goes with door movement is almost always a wire, while a fault that is present constantly from a cold start is more likely the thermistor itself. Note which compartment the display points to before starting; replacing the wrong sensor is the most common wasted repair on this code.

Safe checks for the owner

1. Confirm which display shows OP: OP on the FZ side indicates the freezer thermistor; OP on the FF side indicates the fresh-food thermistor.
2. Check actual compartment temperatures and protect food if cooling is unstable.
3. Disconnect power for five minutes and retry once. Do not remove interior panels if they are frozen in place.

Estimated U.S. repair cost

$220–$480, depending on model, access, parts availability and local labor.