Bosch Cooktop Error Code ER 12

ER 12 indicates a mismatch between the relay port pin assignments in the cooktop's control board hardware and the corresponding software register configuration. The cooktop detects that the physical state of a relay output does not match what the control software expects to find in its register. This is an internal logic fault that causes the cooktop to restrict or shut down operation to prevent uncontrolled heating. The fault is centered on the main control board.

A power reset, performed by turning off the circuit breaker for one to two minutes and restoring power, may temporarily clear ER 12 if the fault was caused by a transient voltage event or a one-time register corruption. However, if the underlying cause is a hardware fault on the control board or permanently corrupted firmware, the error will return shortly after the cooktop resumes operation. A persistent ER 12 after multiple resets indicates a component-level failure that requires repair.

Repair costs depend on whether the fault requires a main control board replacement or only a wiring correction. A replacement control board for a Bosch cooktop typically ranges from roughly 150 to 400 dollars for the part alone, depending on the specific model. Adding professional labor, total repair costs commonly fall between 250 and 600 dollars or more. Getting a firm diagnostic quote from a technician before authorizing parts is advisable, as the exact board part number varies by cooktop model.

In most cases, resolving ER 12 requires replacing the main control board, which involves working inside the appliance and handling high-voltage connections. A knowledgeable DIYer comfortable with appliance disassembly and electrical safety precautions may be able to perform the repair, but it is generally recommended to have a qualified technician handle it. Before replacing the board, verify that all internal wiring harness connections are secure and that the cooktop is receiving stable power.

No, you should not continue using the cooktop while ER 12 is active. This error indicates the control board cannot reliably verify the state of the relay outputs that control power to the heating elements. Continuing to operate the appliance under this condition could result in unpredictable heating behavior, including elements failing to shut off as commanded. Power down the cooktop at the circuit breaker until the fault is diagnosed and repaired.