mypros+
Error code reference

Magic Chef Microwave Error Code Err 3

The temperature sensor is disconnected.

Magic Chef codesMagic Chef microwave codes

The temperature sensor is disconnected.

First step from the service manual

Unplug the power and call technical service.

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

MyPros+ Max

Get the full diagnostic procedure for Err 3.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What Err 3 means on a Magic Chef microwave

Err 3 on a Magic Chef microwave indicates that the temperature sensor has been detected as disconnected from the control circuit. The temperature sensor, typically a thermistor, monitors internal cavity or component temperatures to prevent overheating and to support cooking functions that rely on heat-based feedback. When the control board cannot detect a signal from this sensor, it triggers Err 3 and halts normal operation as a protective measure.

The most common reasons for this fault are a loose or disconnected wiring harness connector at the sensor or at the control board, a broken wire in the sensor circuit, or a failed sensor that no longer completes the circuit. Physical vibration over time can cause connectors to work loose, and the sensor itself can fail open, which the control board interprets as a disconnection.

Because diagnosing and repairing this fault involves working inside the microwave cabinet, which contains a high-voltage capacitor that can retain a lethal charge even after the unit is unplugged, the recommended first step is to unplug the appliance and contact technical service. Technicians should discharge the capacitor before inspecting any internal wiring or components related to this fault.

Source: manufacturer service documentation.

Common causes of Err 3

  1. 01

    Loose or disconnected sensor connector

    Wiring / connection

    The wiring harness connector at the temperature sensor or control board may have come loose over time due to vibration. Visually inspecting the connector for a secure fit is the first step a technician should take after safely discharging the capacitor.

  2. 02

    Failed temperature sensor (open circuit)

    Part replacement

    The thermistor can fail in an open-circuit condition, which the control board reads as a disconnected sensor. A technician can confirm this by measuring the sensor's resistance and comparing it against the expected value.

  3. 03

    Damaged or broken sensor wiring

    Part replacement

    A wire in the sensor circuit may be broken or pinched, interrupting continuity between the sensor and the control board. A technician should inspect the wire run for any visible damage or breaks.

  4. 04

    Faulty control board

    Part replacement

    If the sensor and all associated wiring test correctly, the control board itself may have a defect preventing it from reading the sensor signal. This is a less common cause but should be considered after other components are ruled out.

See the test procedure for each cause

Frequently asked questions about Err 3

What does Err 3 mean on a Magic Chef microwave?
Err 3 means the microwave's control board has detected that the temperature sensor is disconnected from the circuit. The temperature sensor monitors heat levels inside the unit to keep it operating safely. When this signal is lost, the microwave stops functioning and displays the error code. The unit should be unplugged and inspected by a qualified technician.
Can I fix Err 3 on my Magic Chef microwave myself?
This repair is not recommended as a DIY project for most homeowners. The interior of a microwave contains a high-voltage capacitor that can hold a dangerous charge even after unplugging the unit. Diagnosing Err 3 requires safely discharging that capacitor before inspecting wiring or sensor components, which is a task best left to a trained appliance technician.
Will resetting my Magic Chef microwave clear Err 3?
Unplugging the microwave and plugging it back in may temporarily clear the display, but Err 3 will return if the underlying issue with the temperature sensor or its wiring has not been resolved. A reset does not fix a disconnected sensor or a broken wire. The root cause must be identified and corrected for the error to go away permanently.
Is it safe to use my Magic Chef microwave while Err 3 is displayed?
No. Err 3 indicates the microwave cannot monitor its internal temperature, which means a key safety system is not functioning. Continuing to operate the unit in this condition could pose an overheating risk. The microwave should be unplugged until the fault is properly diagnosed and repaired.
How much does it cost to repair Err 3 on a Magic Chef microwave?
Repair costs depend on what component has failed. If the fix is simply reseating a loose connector, a service call fee in the range of $50 to $100 may be the primary cost. Replacing a failed temperature sensor typically adds $20 to $60 in parts. A control board replacement would be more expensive, potentially ranging from $80 to $200 or more including labor, at which point comparing the repair cost to the price of a new unit is worth considering.

Related Magic Chef microwave codes

All Magic Chef microwave codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass