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Error code reference

Frigidaire Microwave Error Code F31

Shorted RTD sensor probe or wiring problem.

Frigidaire codesFrigidaire microwave codes

Shorted RTD sensor probe or wiring problem.

First step from the service manual

Check wiring in probe circuit for possible open or short condition. Check RTD resistance at room temperature and compare to probe resistance chart. If resistance does not match, replace the RTD sensor probe. Let oven cool down and restart. If problem persists, replace EOC.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F31 means on a Frigidaire microwave

The F31 error code on a Frigidaire microwave indicates a shorted RTD (Resistance Temperature Detector) sensor probe or a problem in the probe wiring circuit. The RTD probe is a temperature-sensing component that changes its electrical resistance in proportion to temperature. The EOC (Electronic Oven Control) continuously monitors this resistance to determine cooking cavity temperature. When the control detects a resistance value that falls outside the expected range for a shorted condition, it triggers the F31 fault and halts operation to prevent damage or unsafe cooking.

The most direct diagnostic approach involves inspecting the wiring in the probe circuit for any visible open or short condition, including damaged insulation, pinched wires, or loose connector terminals. After confirming wiring integrity, the RTD probe's resistance should be measured at room temperature and compared against the probe resistance chart specific to the unit. A correctly functioning RTD probe will produce a resistance reading that aligns with the chart at a known ambient temperature. A reading that deviates significantly indicates a failed probe.

If the wiring and probe resistance both check out correctly, the fault may originate in the EOC itself, which processes the sensor signal. Allowing the microwave to cool completely before restarting can rule out a heat-related transient fault. If the F31 code returns after the oven has cooled and the probe and wiring have been confirmed good, replacing the EOC is the next indicated step. This progression isolates the fault systematically from the most accessible and least expensive components to the control board.

Source: manufacturer service documentation.

Common causes of F31

  1. 01

    Shorted RTD probe

    Part replacement

    The RTD sensor probe itself has failed internally, causing a resistance reading outside the acceptable range. Measuring the probe resistance at room temperature and comparing it to the resistance chart will confirm this failure.

  2. 02

    Damaged or shorted probe wiring

    Wiring / connection

    The wiring harness connecting the RTD probe to the EOC may have pinched, burned, or frayed insulation creating a short circuit. Visually inspect the full length of the wiring and check connector terminals for damage or corrosion.

  3. 03

    Loose or corroded connector at the probe or control

    Wiring / connection

    A poor connection at either end of the probe circuit can produce erratic resistance readings that the EOC interprets as a short. Check that all connectors are fully seated and free of corrosion.

  4. 04

    Heat-related transient fault

    Wiring / connection

    Overheating in the cavity or surrounding components can temporarily cause the probe circuit to read out of range. Allowing the unit to cool completely and restarting may clear the code if no component has permanently failed.

  5. 05

    Failed EOC (Electronic Oven Control)

    Part replacement

    If the probe resistance matches the chart and wiring is intact, the EOC may be misreading or misinterpreting the sensor signal due to an internal board fault. Replacing the EOC is the indicated step after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about F31

What does F31 mean on a Frigidaire microwave?
F31 indicates a shorted RTD sensor probe or a wiring problem in the probe circuit. The RTD probe monitors cooking cavity temperature by changing its electrical resistance with heat, and the control board detected a resistance value consistent with a short. The microwave stops operating when this code appears to prevent unsafe conditions.
Can I fix the F31 error myself?
A knowledgeable DIYer can inspect the probe wiring for visible damage and check connector integrity without special tools. Measuring RTD resistance requires a multimeter and access to the probe resistance chart for your specific model. If the probe resistance is out of spec, replacing the RTD sensor probe is a straightforward repair, though replacing the EOC is more involved and may be better handled by a technician.
Will resetting the microwave clear the F31 code?
Resetting by unplugging the unit or cycling the breaker may temporarily clear the code, but it will return if the underlying fault in the probe or wiring is not corrected. Letting the oven cool completely before restarting is a recommended first step, as a heat-related transient can sometimes trigger F31. A persistent F31 code after cooling and restarting requires hands-on diagnosis.
Is it safe to use my Frigidaire microwave while the F31 code is displayed?
No, you should not continue using the microwave while F31 is active. The error indicates the temperature monitoring system is not functioning correctly, which means the control cannot accurately track cooking cavity temperature. Operating the unit in this condition could result in overheating or unsafe operation.
How much does it cost to repair a Frigidaire microwave F31 error?
Repair costs depend on which component has failed. An RTD sensor probe is generally an affordable part, with the probe itself typically ranging from $15 to $50 depending on the model. If the EOC requires replacement, parts alone can range from $80 to $200 or more, and professional labor will add to the total cost. Getting a diagnosis before ordering parts is recommended to avoid unnecessary expense.

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