Bertazzoni Dishwashers F42 Error: Thermistor (NTC sensor) fault
What Does F42 Mean on a Bertazzoni Dishwasher? Error code F42 indicates that the main control board is not receiving a valid signal from the NTC temperature sensor (thermistor). The thermistor is a small temperature-sensitive resistor that tells the PCB the exact water temperature at all times. At 20°C it should measure approximately 60 kΩ […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
Maybe. The dishwasher can run cycles but without accurate temperature control. Dishes will not be reliably sanitized and wash quality is unpredictable. The machine is not dangerous to operate in this state, but repeated cycling is not recommended until the sensor is replaced.
Can I reset the code?
Yes. A power-cycle may clear F42 temporarily if the fault is caused by a marginal connector connection rather than a fully failed thermistor. However, F42 will return consistently each cycle if the thermistor or its circuit is genuinely faulty.
When to stop immediately?
Stop if you notice: F42 appears on every single cycle without exception, preventing any normal wash from completing, A burning smell is detected — this is unrelated to F42 but warrants stopping immediately.
Symptoms You May Notice
Wash cycle uses incorrect water temperatures or aborts during heating
Without a valid temperature signal, the control board cannot confirm when target temperatures are reached. Cycles may run with tepid water, overshoot temperature, or abort early — resulting in poor cleaning and no sanitization.
F42 appears consistently at the beginning of the heating phase
Unlike intermittent temperature faults, F42 triggered by a failed thermistor appears reliably at the same point in every cycle — the moment the board first polls the sensor at the start of heating.
Dishes are poorly cleaned despite cycle running to completion
When the PCB operates with a faulty sensor reading, wash temperature management is unreliable. Some cycles may complete but with water that never reached the intended temperature for effective cleaning.
Possible Causes
Thermistor element failed — open or short circuit
The NTC thermistor is an epoxy-encapsulated resistor whose resistance changes predictably with temperature. At 20°C it should measure approximately 60 kΩ. An open-circuit thermistor reads infinite resistance; a shorted one reads near zero. Either condition is immediately detected as F42.
Requires ProfessionalWiring connector corroded or broken at thermistor plug
The thermistor connector sits in the wet underside of the tub sump area. Corrosion or a broken terminal pin produces the same out-of-range signal as a failed sensor and should be ruled out before replacing the thermistor.
Requires ProfessionalPCB input circuitry damaged — cannot read thermistor signal
Moisture ingress or a voltage spike can damage the PCB circuit that reads the thermistor. If a confirmed-good replacement thermistor also triggers F42, the PCB is at fault.
Requires ProfessionalSafe Checks You Can Do
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1
Power-cycle and note exactly when F42 appears
Cut power at the circuit breaker for 60 seconds, restore, and start a cycle. Note precisely when F42 appears — immediately on power-up, at cycle start, or only once the heating phase begins. This timing information is useful diagnostic data for your technician.
F42 appearing immediately at power-on before any cycle action suggests an open-circuit thermistor or disconnected connector. F42 appearing only during heating suggests a borderline sensor that fails under thermal stress.
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2
Check for obvious connector issues (if comfortable doing so)
With power OFF at the breaker, remove the lower toe-kick panel. Using a torch, look for any obviously loose, corroded, or disconnected connectors in the base area. A connector that has simply backed off its housing can sometimes be pressed back in firmly.
Do not probe or disconnect any connectors while power is on. Always verify the breaker is off before reaching into the base area.
Tools required -
3
Document wash results for the technician
Note whether cycles are completing, aborting, or running to completion with poor cleaning. Record which cycle programs trigger F42 most consistently. This documentation helps a technician diagnose quickly on arrival.
A photo of the F42 display can also be useful, especially if the fault is intermittent.
When to Call a Professional
Contact a qualified technician if:
- F42 returns on every cycle after power-cycling
- Thermistor resistance at room temperature reads significantly above or below 60 kΩ
- A replacement thermistor also triggers F42 immediately, suggesting PCB input damage
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