On the covered Thermador Masterpiece wall oven, E218 means a failure of the lower oven cooling fan. First, cut power and check the fan and its speed sensor's wiring. Then: reseat connectors and replace damaged harnesses. A fan that does not run when asked is replaced, and if the fan runs normally the speed sensor (the hall sensor) is replaced.
Try in this order
0 of 8 completedWhat to do first
ReversibleCut power and check the fan and its speed sensor's wiring.
Correct only the documented fault domain
ReversibleReseat connectors and replace damaged harnesses. A fan that does not run when asked is replaced, and if the fan runs normally the speed sensor (the hall sensor) is replaced.
Check the fan and its sensor wiring
ReversibleWith the power off, check the harness connections on the lower oven cooling fan and on its hall sensor, the tachometer that tells the control the fan is turning. Reseat loose plugs or replace a damaged harness.
Decide between the fan and the sensor
ReversibleIf the fan does not run when activated, replace the fan. If it runs properly, the hall sensor is the part to replace; if both test well, a damaged wire or the main board is what remains.
Let the oven cool and switch it off
ReversibleTurn the oven off at the breaker and let it cool completely before you do anything else, since the fan exists to remove heat from the electronics.
Listen for the fan
ReversibleWith the power back on and the oven off, listen at the vents for the cooling fan starting. A fan that does not spin, spins slowly or rattles is what the code is about.
Check the vents
ReversibleMake sure nothing blocks the vents around the oven and that the cabinet is not trapping heat.
Book a technician for the fan or its sensor
ReversibleThermador's service table lists the lower-oven cooling fan and its hall sensor as the parts to replace, and both sit inside the oven.
Evidence ledger
Sources behind this answer
Exact questions
Common questions about “Thermador Masterpiece wall oven code E218”
What does E218 mean on a Thermador Masterpiece wall oven?+
a failure of the lower oven cooling fan.
Can I keep using the upper oven with E218 on the lower?+
Oven repair guides treat a cooling fan fault as a reason to stop using that oven until it is fixed, since the fan protects the cabinet from heat.
Is it safe to use the oven when the cooling fan has failed?+
The fan keeps the electronics and the door cool, so avoid running long, hot cycles on the affected oven until it is repaired; the other oven can be used as normal.
Can I replace the cooling fan myself?+
The service table says to disconnect power and check the wire harness at the fan first, but the fan and its hall sensor sit inside the oven, so replacing them is a job for a service technician.
Should I turn the lower oven on to test the fan?+
Not repeatedly. Run it briefly to see whether the fan starts, and stop if the fan does not spin or the oven or cabinet gets unusually hot.
What does the cooling fan do on a wall oven?+
It moves air through the control compartment and around the cavity so the electronics and the cabinet stay cool while the oven is hot.
Will the upper oven still work while the lower one shows E218?+
The page's source says the fault is for the lower oven, so the upper oven can usually be used normally. Avoid long, high-temperature use of the lower oven until it has been repaired.