mypros+
Error code reference

Hotpoint Cooktop Error Code F08

ISI UART 2 (CN 04) inductor NTC fault on small induction hotplate

Hotpoint codesHotpoint cooktop codes

ISI UART 2 (CN 04) inductor NTC fault on small induction hotplate — subcode 1: NTC short circuit; subcode 2: NTC open circuit; subcode 3: small induction hotplate not connected.

First step from the service manual

Check the inductor, verifying that the contacts are well connected and clean.

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 F08.

  • 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 F08 means on a Hotpoint cooktop

The F08 error code on a Hotpoint induction cooktop indicates a fault in the NTC (Negative Temperature Coefficient) thermistor associated with the small induction hotplate connected through the ISI UART 2 communication interface at connector CN 04. The NTC thermistor is a temperature-sensing resistor embedded in or near the inductor coil assembly. Its resistance changes predictably as temperature rises, allowing the control board to monitor hotplate temperature and prevent overheating. When the control board detects an abnormal signal from this sensor, it logs F08 and disables the affected burner zone as a safety measure.

The error is further defined by three subcodes that pinpoint the specific failure mode. Subcode 1 indicates an NTC short circuit, meaning the thermistor resistance has dropped abnormally low, simulating an extreme high-temperature reading. Subcode 2 indicates an NTC open circuit, where the thermistor or its wiring has broken continuity entirely, producing no usable signal. Subcode 3 means the small induction hotplate itself is not detected by the UART 2 interface, which can point to a disconnected or failed inductor assembly rather than a thermistor fault specifically.

Because the first diagnostic step is to inspect the inductor and verify that all contacts at CN 04 are clean and fully seated, many F08 occurrences are traced to loose connectors or corrosion on the terminal pins rather than outright component failure. If connection integrity checks out, resistance testing of the NTC thermistor and inspection of the wiring harness between the inductor and the control board are the next logical steps.

Source: manufacturer service documentation.

Common causes of F08

  1. 01

    Loose or dirty connector at CN 04

    Wiring / connection

    The connector linking the small induction hotplate to the ISI UART 2 interface may have worked loose or accumulated grease and debris on its terminals. This is the first thing to check, as poor contact can mimic both open-circuit and disconnection faults.

  2. 02

    NTC thermistor open circuit (Subcode 2)

    Part replacement

    The NTC thermistor embedded in the inductor assembly can fail by breaking internal continuity, producing no resistance reading at all. This shows as subcode 2 and requires replacement of the thermistor or the inductor coil assembly if the sensor is not serviceable separately.

  3. 03

    NTC thermistor short circuit (Subcode 1)

    Part replacement

    A shorted NTC thermistor will show abnormally low resistance, causing the control board to read an impossibly high temperature and shut down the zone. Subcode 1 confirms this condition, and the thermistor or inductor assembly will need replacement.

  4. 04

    Small induction hotplate not connected or detected (Subcode 3)

    Part replacement

    Subcode 3 means the control board cannot communicate with the small hotplate inductor at all through the UART 2 channel. This can result from a disconnected wiring harness, a failed inductor coil, or internal damage to the hotplate assembly.

  5. 05

    Damaged wiring harness between inductor and control board

    Part replacement

    Chafed, pinched, or heat-damaged wiring between the inductor assembly and the main control board can produce open-circuit or intermittent faults that register as F08. Visually inspect the harness routing for any signs of insulation damage or broken wires.

See the test procedure for each cause

Frequently asked questions about F08

What does F08 mean on a Hotpoint cooktop?
F08 indicates a fault with the NTC temperature sensor on the small induction hotplate, specifically on the ISI UART 2 circuit at connector CN 04. The fault has three subcodes: subcode 1 is an NTC short circuit, subcode 2 is an NTC open circuit, and subcode 3 means the small hotplate is not being detected at all. The cooktop disables the affected burner zone when this error is active to prevent unsafe operation.
Can I fix F08 on my Hotpoint induction cooktop myself?
The first diagnostic step is something a confident DIYer can attempt: checking that the inductor's connector at CN 04 is fully seated and that the contacts are clean and free of corrosion. If reseating the connector does not clear the fault, further diagnosis involves testing the NTC thermistor resistance and inspecting the wiring harness, which requires disassembly and a multimeter. Replacing the inductor coil assembly or control board is a more advanced repair that many homeowners prefer to leave to a qualified technician.
Is it safe to keep using the cooktop with an F08 error?
The cooktop disables the affected small induction burner zone when F08 is active, so that specific zone will not operate. Other burner zones may still function depending on the cooktop model. It is not advisable to continue using the appliance without addressing the fault, as the underlying sensor failure means the overtemperature protection on that burner is compromised.
Will resetting the cooktop clear the F08 error?
A power reset by switching off the cooktop at the circuit breaker for a few minutes may temporarily clear the error if it was caused by a momentary communication glitch or a connector that reseated itself. However, if the NTC thermistor is genuinely shorted, open, or the hotplate is not properly connected, the F08 code will return once power is restored and the control board runs its diagnostics. A reset is not a repair.
How much does it cost to repair an F08 error on a Hotpoint induction cooktop?
Repair costs vary depending on which component has failed. If the issue is simply a loose or dirty connector, there may be no parts cost at all, just a service call fee which typically ranges from $75 to $150. Replacing an NTC thermistor or inductor coil assembly can add $80 to $250 or more in parts, depending on availability. If the main control board is involved, total repair costs including labor can range from $200 to $450 or higher.

Related Hotpoint cooktop codes

All Hotpoint cooktop codes
View all 18 Hotpoint cooktop codes

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

Get Started

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