What this error means
Heating system fault — the dishwasher is not reaching the correct wash temperature
The F13 error means the Miele dishwasher has failed to heat the water to the required temperature within the allowed time, or the temperature sensor has returned an out-of-range reading. The most common causes are a failed heating element (flow heater), a faulty NTC thermistor, or heavy limescale build-up on the element. Miele dishwashers use a flow-through heater rather than a static element — this is a different component to the element in a washing machine and requires a different approach.
Step-by-step
Symptoms to look for
- Dishes coming out cold, greasy, or with undissolved detergent after a hot programme
- Interior of the dishwasher feels no warmer than room temperature during a cycle
- F13 displayed partway through a wash or rinse programme
- Programme runs significantly longer than the Miele display estimate before faulting
Diagnostic steps
Unplug for 5 minutes to reset the board. Plug back in and run Intensive or 70 degrees with no load. After 15 minutes, carefully open the door a few centimetres. You should feel warm to hot steam immediately. If the interior feels no warmer than room temperature the flow heater is not working.
Add a Miele dishwasher descaling tablet to the base of the tub — Miele recommends their own Descaler product — and run a full 65-degree empty programme. Miele flow-through heaters accumulate limescale in the internal channels over time, restricting water flow through the heater and reducing heat transfer. This is the most common cause of gradual F13 development on Miele machines.
Open the Miele salt port on the floor of the tub. If empty or very low, top up with coarse Miele-approved dishwasher salt. Miele machines use a precision ion exchange water softener — running without salt allows hard water to pass through the heating circuit unconditioned, causing rapid limescale accumulation inside the flow heater.
With the dishwasher completely unplugged, the flow heater on a Miele dishwasher is typically accessed from beneath the machine after pulling it out from its housing. It is a cylindrical or rectangular component in the water circulation circuit with inlet and outlet hoses and two electrical terminals. Inspect it for external signs of leakage, cracking, or limescale build-up around the ports.
With the dishwasher unplugged and the wiring disconnected from the heater terminals, test across the two main power terminals with a multimeter. A healthy Miele flow heater typically reads between 20 and 40 ohms. An OL (open circuit) reading confirms the heater has failed.
The NTC sensor is mounted on or near the flow heater body, connected by two thin wires. Disconnect its connector and test across the terminals. At room temperature a healthy Miele dishwasher NTC reads between 4,000 and 12,000 ohms. A zero or OL reading means the sensor has failed.
When to call an engineer
- Flow heater reads outside 20 to 40 ohms or shows continuity to earth — heater has failed
- NTC thermistor reads open circuit or zero — sensor has failed
- Flow heater confirmed blocked with limescale that cannot be cleared by descaling — heater replacement required
- F13 persists after descaling and sensor check — contact Miele service
Frequently asked questions
What is a flow heater and how is it different from a standard dishwasher element?
Can limescale alone cause F13 without the flow heater being broken?
How often should I descale my Miele dishwasher?
Should I use Miele's own descaling products?
🎯 What is likely causing this fault?
⚠️ Estimates based on common faults — not a guaranteed diagnosis. Always verify before ordering parts.