Miele Washing Machine Error Code F138 — Waterproof System Activated
What this means
Error F138 is Miele's Waterproof system alert for washing machines — equivalent to F70 on dishwashers. The float switch in the base has detected water, indicating a leak somewhere in the machine. The machine immediately stops the cycle, locks the door, and activates the drain pump. Common leak sources include a perished door seal, loose hose clamps, a cracked tub, a leaking pump seal, or a faulty inlet valve.
Alternate codes: F 138
Step-by-step fix
4 stepsTurn off water and power
Shut off the water supply taps and turn off the machine at the circuit breaker. Mop up any visible water around the machine.
The drain pump may run continuously when F138 is active — this is normal safety behavior.
Inspect the base pan
Carefully tilt the machine backward (have someone help) and look at the base. Or remove the rear panel and shine a flashlight at the base. Note the amount of water and where it seems to be coming from.
Miele machines are heavy — use caution when tilting. Better to slide the machine out and access from the front.
Identify the leak source
Common leak points: the door seal (check for tears, foreign objects, or detergent buildup on the seal surface), the sump hose connections, the drain pump gasket, the inlet hose connections, and the detergent drawer housing.
Place dry paper towels at various points and run a short fill cycle to identify which area gets wet first.
Dry the base and reset the float switch
After fixing the leak, thoroughly dry the base pan. The float switch (a small Styrofoam or polystyrene float) should drop back down once the water is removed. Reassemble and run a test cycle while monitoring for leaks.
If the float switch is stuck in the up position, gently press it down. Limescale can cause it to stick.
When to call a professional
If the leak is from the drum bearings (rear of the drum), the outer tub, or an internal hose that is difficult to access, professional repair is needed.
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
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