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Error code reference

GE Dryer Error Code tO

Thermistor open circuit detected.

GE codesGE dryer codes

Thermistor open circuit detected.

First step from the service manual

Check Thermistor's connector and wiring.

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

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What tO means on a GE dryer

The tO error code on a GE dryer indicates that the control board has detected an open circuit condition in the thermistor circuit. The thermistor is a temperature-sensing resistor whose resistance changes predictably with temperature, allowing the control board to monitor drum air temperature in real time. An open circuit means the electrical path through the thermistor or its associated wiring is completely broken, so no resistance reading can be transmitted to the control board. When the board receives no signal from the thermistor, it cannot regulate heating and will shut down or lock out the heating circuit to prevent overheating.

The thermistor is typically mounted in the dryer's exhaust duct or air path and connects to the main control board via a low-voltage wiring harness. Because this is a low-current sensing circuit, even minor connection issues such as a loose connector pin, corroded terminal, or a single broken wire can interrupt the signal entirely and trigger the tO fault. The thermistor component itself can also fail internally, breaking the resistive element and creating the same open-circuit condition the code describes.

Diagnosis should begin at the thermistor connector and wiring harness, inspecting for any pins that have backed out of the connector housing, signs of heat damage, or corrosion at the terminals. If the wiring appears intact, the thermistor itself should be tested with a multimeter for continuity and proper resistance across its temperature range. A functioning thermistor will show measurable resistance rather than an open (infinite) reading.

Source: manufacturer service documentation.

Common causes of tO

  1. 01

    Loose or disconnected thermistor connector

    Wiring / connection

    The wiring connector at the thermistor or at the control board may have vibrated loose or have a pin that has backed out of the housing. Inspect both ends of the connector for secure seating and proper pin engagement.

  2. 02

    Failed thermistor

    Part replacement

    The thermistor's internal resistive element can break, creating a permanent open circuit. Testing with a multimeter will show infinite resistance (no continuity) across the thermistor terminals when it has failed internally.

  3. 03

    Broken or damaged wiring in the harness

    Wiring / connection

    A wire in the thermistor harness can break internally while still appearing intact from the outside, especially near stress points like wire ties or routing clips. Inspect the harness along its full length and perform a continuity check on each wire.

  4. 04

    Corroded connector terminals

    Wiring / connection

    Moisture in the laundry environment can cause oxidation on the low-voltage connector terminals, increasing resistance to the point where the board reads the circuit as open. Look for green or white oxidation deposits on the pins and sockets.

  5. 05

    Faulty control board

    Part replacement

    If the thermistor and all wiring test correctly, the control board's thermistor input circuit may have failed and is incorrectly reporting an open condition. This is the least common cause and should only be considered after all wiring and sensor checks are complete.

See the test procedure for each cause

Frequently asked questions about tO

What does tO mean on a GE dryer?
The tO code on a GE dryer means the control board has detected an open circuit in the thermistor, which is the component that monitors drying temperature. An open circuit means the electrical path carrying the temperature signal is broken, so the board cannot read any temperature data. The dryer will typically disable heating until the fault is resolved. The issue is most often caused by a loose connector, a broken wire, or a failed thermistor.
Can I fix the tO error code myself?
Many cases of the tO error can be resolved without professional help by checking the thermistor's wiring connector and ensuring it is fully seated. If the connector looks secure, use a multimeter to test the thermistor for continuity. A thermistor that reads infinite resistance has failed and needs replacement, which is a straightforward part swap for most DIYers comfortable working inside appliances.
Is it safe to keep using my dryer when the tO code is showing?
You should not continue running the dryer with the tO error active. Because the control board cannot read temperature from the thermistor, it cannot properly regulate the heating element. This creates a risk of overheating the drum and laundry load. Stop using the dryer until the thermistor circuit is inspected and repaired.
Will resetting the dryer clear the tO error code?
A reset may temporarily clear the tO code from the display, but the fault will return as soon as the dryer starts and the control board again detects no signal from the thermistor. The underlying open circuit in the thermistor wiring or the sensor itself must be repaired before the code will stay clear.
How much does it cost to fix the tO error on a GE dryer?
If the fix is simply reseating a loose connector, there is no parts cost involved. A replacement thermistor typically costs in the range of $15 to $40 for the part. If a professional technician is needed for diagnosis and repair, total service costs including labor generally fall in the range of $80 to $200 depending on your location and the extent of the repair.

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