What F3 Means
WHICH MACHINES THIS APPLIES TO: F3 as a single character is a DW20 and DW70 platform code. The DW20 boards are the ones sold in the US as the 3000 and 5000 Series. On current DBI, DFI and DSD machines there is no F3; the thermistor fault there carries a two-digit number.
DW20 AND DW70 PLATFORM - WHAT F3 MEANS: the service manual reads "Thermistor fault. Interruption or greater than 80 degrees Celsius. The programme exits from the heating stage and continues in the process. Indication only in the service menu." The thermistor is the temperature sensor in the wash chamber. Two conditions trigger the code: the circuit going open, which the control reads as an interruption, or the sensor reporting a temperature above 80 degrees Celsius, which on a dishwasher is not a plausible wash temperature and is treated as a sensor error rather than as real heat.
WHAT THE MACHINE DOES NEXT: it abandons the heating stage and finishes the programme without it. Nothing stops, nothing floods, and the owner is shown no message - the manual is explicit that the indication is in the service menu only. The symptom people actually notice is a wash that is not getting hot and a drying result that has quietly got worse.
CLASSIFICATION: fault. The machine keeps working, but it is not doing the job it reports doing.
Common Causes of F3
- Break in the thermistor circuit, in the sensor or in its wiring
- Connector to the thermistor loose or corroded
- Thermistor drifted and reporting above 80 degrees Celsius
- Control unit misreading an otherwise sound sensor
🔧 One Safe Check You Can Try
Nothing here is an owner repair, and there is no display message to clear, so the useful work is narrowing the picture for whoever does open the machine. Run a hot programme and feel the inside of the door and the top of the load at the end: a genuine thermistor fault usually means the load is barely warm, whereas a wash that is hot but still leaving the glassware cloudy is a different problem entirely. Note whether the fault is constant or intermittent, because an intermittent open circuit usually points at a connector rather than the sensor itself. Leave the machine isolated at the outlet or the breaker if a technician is coming, and do not attempt to reach the sensor: on these machines it is mounted at the sump, underneath the tub, and getting to it means drawing the dishwasher out of the cabinet with the plumbing still connected.
⚠ Why You Shouldn't Go Further Than That
- The thermistor sits at the sump beneath the wash tub, so the dishwasher has to be isolated from power, unfastened and drawn out of the cabinet before it is reachable at all.
- The sensor wiring runs in the same loom as the element and pump supply, which is live whenever the machine is connected to power.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.