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Error code reference

Hotpoint Cooktop Error Code F16

ISI UART 2 (CN 04)

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ISI UART 2 (CN 04): Excessively high temperature on the large induction coil.

First step from the service manual

Check whether the induction coil NTC has become miscalibrated.

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

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What F16 means on a Hotpoint cooktop

The F16 error code on a Hotpoint induction cooktop indicates that the ISI UART 2 communication channel (connector CN 04) has detected an excessively high temperature reading on the large induction coil. The induction coil assembly uses an NTC (Negative Temperature Coefficient) thermistor as a temperature sensor. This NTC thermistor changes its resistance value in response to heat: as temperature rises, resistance drops. The cooktop's control board continuously monitors this resistance to track coil temperature and prevent thermal damage to the inverter circuitry and coil itself.

When the board receives a signal indicating the large coil has exceeded its safe operating temperature threshold, it triggers the F16 fault and typically shuts down that cooking zone. The first diagnostic priority is determining whether the temperature reading reflects an actual overheat condition or a sensor calibration fault. An NTC that has drifted out of calibration can report falsely elevated temperatures even when the coil is operating within normal thermal limits. This is why the first diagnostic step focuses specifically on checking whether the NTC has become miscalibrated.

Possible root causes include a genuinely overheated coil due to blocked ventilation, a failed or drifting NTC thermistor, poor contact between the NTC and the coil surface, wiring faults on the CN 04 connector, or a fault in the control board's input circuit for that sensor channel. Proper diagnosis requires measuring the NTC resistance at a known temperature and comparing it against the expected resistance curve to determine if the sensor is reading accurately.

Source: manufacturer service documentation.

Common causes of F16

  1. 01

    Miscalibrated or failed NTC thermistor

    Part replacement

    The NTC thermistor on the large induction coil can drift out of calibration over time, causing it to report artificially high resistance changes that the control board interprets as extreme heat. Measure the thermistor's resistance at a known ambient temperature and compare it to the expected value to confirm this fault.

  2. 02

    Blocked or restricted ventilation

    Wiring / connection

    Induction cooktops rely on internal fans and clear airflow paths to cool the coil and inverter components. Debris, grease buildup, or a failed cooling fan can cause genuine coil overheating that triggers F16. Inspect the ventilation slots and confirm the cooling fan is spinning freely.

  3. 03

    Poor NTC contact with the coil surface

    Wiring / connection

    If the NTC thermistor has shifted position or its mounting clip has loosened, it may no longer be seated firmly against the coil surface, leading to erratic or inaccurate temperature readings. Visually inspect the sensor mounting and reseat it if necessary.

  4. 04

    Wiring or connector fault at CN 04

    Wiring / connection

    Damaged, corroded, or loose wiring at the CN 04 connector on the ISI UART 2 channel can produce abnormal signals that the control board misinterprets as an overheat condition. Inspect the connector pins for corrosion, bent contacts, or loose crimps and repair as needed.

  5. 05

    Control board input circuit fault

    Part replacement

    If the NTC and wiring both test correctly, the fault may lie in the control board's sensor input circuitry for the large coil channel. A failed component on that circuit can produce a constant high-temperature reading regardless of actual coil conditions, requiring board replacement.

See the test procedure for each cause

Frequently asked questions about F16

What does F16 mean on a Hotpoint cooktop?
F16 indicates that the ISI UART 2 channel (connector CN 04) has detected an excessively high temperature on the large induction coil. The cooktop shuts down the affected zone to prevent component damage. The fault can be caused by a genuine overheat condition or by a miscalibrated NTC temperature sensor reporting a false high reading. A technician will need to evaluate both the sensor and the cooktop's cooling system to determine the true cause.
Can I fix the F16 error myself, or do I need a technician?
Some basic checks, such as clearing blocked ventilation slots or confirming the cooling fan is running, can be done without special tools. However, accurately diagnosing a miscalibrated NTC thermistor requires measuring resistance values and comparing them against a reference curve, which typically requires a multimeter and technical knowledge. Connector inspection at CN 04 and any board-level repairs should be handled by a qualified appliance technician.
Is it safe to keep using my Hotpoint cooktop when F16 is showing?
No, you should not attempt to bypass or ignore the F16 fault and continue cooking. The code indicates a potential thermal fault on the large induction coil, and operating with an unresolved overheat condition or faulty temperature sensor could cause permanent damage to the inverter circuitry or, in the case of a genuine overheat, create a safety risk. The cooktop should remain out of service until the fault is diagnosed and corrected.
Will resetting the cooktop clear the F16 error code?
A power reset may temporarily clear the displayed code, but if the underlying cause, such as a faulty NTC thermistor, a wiring fault, or a blocked cooling path, has not been resolved, the F16 error will return as soon as the cooktop attempts to operate the large coil again. Resetting without diagnosing the root cause is not a lasting fix.
How much does it cost to repair an F16 error on a Hotpoint induction cooktop?
Repair costs vary depending on the root cause. Replacing an NTC thermistor is generally the least expensive fix, typically falling in the range of $50 to $150 including parts and labor. A control board replacement is the most costly scenario, often ranging from $200 to $400 or more depending on the specific model and labor rates in your area. Getting a diagnostic assessment first will help clarify which component is at fault before committing to a repair.

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