Ariston Washer Error Code F03

F03 means the washer has detected a problem with the NTC temperature sensor circuit or the wash heater relay. The NTC thermistor may be open circuit, short circuit, or the heater relay may be stuck closed. The machine stops operation to prevent unsafe water temperatures. The first thing to check is the J8 connector on the main control card, as a poor connection there is a common cause.

No, you should not continue using the washer while F03 is active. If the fault is a stuck heater relay, the heating element could overheat the water to unsafe levels. If it is a failed NTC sensor, the machine cannot regulate wash temperature at all. Stop using the appliance until the fault is diagnosed and resolved.

Repair costs vary depending on the root cause. Replacing an NTC thermistor is generally inexpensive, with parts typically ranging from $10 to $40 and labor adding $50 to $100 if a technician is used. If the control board needs replacement due to a stuck relay, costs can range from $150 to $350 or more depending on parts availability and labor rates. Addressing a simple connector issue may cost nothing if you handle it yourself.

Checking and reseating the J8 connector on the control board is something a confident DIYer can attempt, as it requires no parts and only basic disassembly to access the board. Testing the NTC thermistor with a multimeter is also a manageable task if you are comfortable working with appliance wiring. However, replacing the control board or diagnosing a stuck heater relay is more complex and is generally better handled by a qualified technician.

A power reset may temporarily clear the F03 code, but if the underlying fault persists, the code will return once the machine attempts to heat water again. A reset does not fix a faulty NTC thermistor, damaged wiring, or a stuck relay. It is worth performing a reset only to confirm whether the fault is intermittent or consistent, not as a permanent solution.