Thermador Cooktop Error Code W5

The W5 code means the cooktop's user interface has detected an input voltage reading above the acceptable upper limit. This can be caused by a wiring or connection fault within the cooktop's power supply circuit, or by an actual overvoltage condition at the household mains supply. The unit triggers this fault as a protective measure to prevent damage to its electronics. The appliance must be disconnected from power immediately when this code appears.

Simply resetting or cycling power is unlikely to permanently clear the W5 fault if the underlying voltage problem still exists. Once power is restored to a circuit that is still delivering voltage above the limit, the cooktop will detect the condition again and the code will return. The root cause, whether a wiring fault or a supply voltage problem, must be corrected first.

Repair costs vary depending on the cause. If the issue is a loose wire connection, the fix may cost little beyond a service call fee, typically in the range of $75 to $150. If a faulty circuit breaker is involved, breaker replacement by an electrician generally runs $150 to $350. If the user interface board has failed and requires replacement, parts and labor combined can range from $300 to $700 or more depending on the specific model and labor rates in your area.

No. The W5 error indicates a potentially dangerous electrical condition, and the cooktop should be disconnected from its power supply immediately. Operating the cooktop with an unresolved overvoltage condition risks damage to the control electronics and could create a safety hazard. Do not restore power until the cause of the overvoltage has been identified and corrected.

Start by disconnecting the cooktop from power, then measure the voltage at the dedicated circuit using a calibrated multimeter to determine whether the supply voltage is out of range. Inspect all wiring connections at the terminal block for looseness, incorrect placement, or corrosion. If the supply voltage and wiring both check out correctly, the user interface board may require professional diagnosis. A licensed electrician should be involved if the fault originates at the household panel or utility supply.