What this error means
The F9 error code on your Whirlpool dishwasher means the temperature sensor (NTC thermistor) has developed a fault — the machine cannot accurately measure the water temperature and has stopped the cycle to prevent unsafe or ineffective washing.
The F9 error indicates a fault with the NTC (Negative Temperature Coefficient) thermistor — the temperature sensor that monitors the water temperature throughout the dishwasher cycle. The thermistor's electrical resistance changes in a precise and predictable way as temperature rises and falls, and the control board reads this resistance to determine the current water temperature. If the board receives a reading that is impossible (such as below 0°C or above the machine's maximum), detects no signal at all (indicating a broken sensor), or sees a reading that does not change during heating (suggesting the sensor is stuck), it logs F9 and stops the cycle. The thermistor is typically located at the bottom of the dishwasher near the heating element or in the sump area. It is a relatively inexpensive component, and in many cases replacing it restores the machine to full function. A power reset is always the first step, as a temporary sensor misread can occasionally trigger F9 as a one-off event.
Step-by-step
Symptoms to look for
- F9 displayed on the control panel
- Dishwasher stopping part-way through a cycle during or after the heating phase
- Dishes coming out dirty or greasy due to incomplete or cold washing
- F9 appearing consistently on every full programme
- Machine completing rinse programmes but failing on wash programmes that require heating
Diagnostic steps
Unplug the dishwasher for 2 full minutes, then restart and run a complete programme. If F9 does not appear, the fault was a temporary sensor misread. Monitor over the next few cycles and only book an engineer if F9 returns.
Pay attention to exactly when F9 appears. If it occurs at the very start of the programme (before any heating), the sensor is likely completely open-circuit (broken internally). If it appears after 10–15 minutes of running — during or after the main wash heating phase — the sensor may be drifting out of specification under thermal stress. If it appears only at specific temperatures (e.g. always at 65°C programmes but not 55°C), the sensor is degrading but not yet fully failed. Share these observations with your engineer.
On most Whirlpool dishwashers the NTC thermistor is clipped into the sump area at the bottom of the machine, adjacent to the heating element. It typically looks like a small cylindrical plastic component — roughly the size of a watch battery — with two thin wires leading to a connector. It is accessible after removing the lower basket and filter assembly, and in some cases after removing the lower spray arm.
A qualified engineer will disconnect the thermistor and measure its resistance with a multimeter at room temperature. Most NTC thermistors used in Whirlpool dishwashers should read between 4,000 and 15,000 ohms at room temperature (consult the service manual for the precise value for your model). An open circuit reading (infinite resistance) confirms the sensor has failed. A reading within range at room temperature but failing when warm may require monitoring during a live cycle.
Replacing the NTC thermistor involves removing the lower basket, filter assembly, and lower spray arm to access the sump area, disconnecting the wiring connector, unclipping or unthreading the old thermistor, and fitting the new component. The machine should then be reassembled and tested on a full programme at the highest temperature available.
When to call an engineer
- F9 returns after power reset on every programme
- Thermistor shows open circuit on multimeter test at room temperature
- Thermistor reads correctly at room temperature but F9 appears under thermal load
- F9 persisting after thermistor replacement (possible PCB fault or wiring fault)
- Burn marks or corrosion visible on thermistor connector or adjacent wiring
Frequently asked questions
What does F9 mean on a Whirlpool dishwasher?
Is F9 on a Whirlpool dishwasher expensive to fix?
Can I fix F9 on a Whirlpool dishwasher myself?
Why does F9 only appear part-way through a cycle on my Whirlpool dishwasher?
What is an NTC thermistor in a dishwasher?
🎯 What is most likely causing your Whirlpool F9 error?
⚠️ Estimates based on common faults — not a guaranteed diagnosis. Always verify before ordering parts.
Parts you may need
Enter your model number to filter results to your exact machine
Usually found on a label inside the door frame or on the back panel of the machine.
| Part | Approx. UK Cost | Find it |
|---|---|---|
| NTC Thermistor | £10 - £20 | 🏷️ eBay UK → |
| Heating element | £20 - £30 | 🏷️ eBay UK → |
ℹ️ Prices are approximate. Always check the part number matches your model before ordering. Not sure of your model number? Find out how to locate it here.