HBL5750UC/08 Bosch Wall Oven. Broiler element comes on / stays on in all cook modes.

Bosch wall oven, microwave combo, HBL5750UC/08

Problem:

• In any cook mode but off, broiler element comes on and stays on. This used to happen intermittently, now all the time.
• Eventually the over-temp sensor will trigger and turn it off.
• Turning oven to "off" will turn off broiler element.

• Built-in diagnostics (from downloaded service manual) don't show any relevant faults.
• Temp readings from sensors (again, using built-in diagnostics) seem accurate.
• Using diagnostics to turn on broil element turns it on, but again, will never turn off.

All of this leads me to believe it is a stuck relay?

Question:

I've seen references to a "control/relay board" and a "relay board". I suspect one of these components.

Control/Relay board comes up as Bosch part #12022212. This board looks like it has many small relays on it.

Relay board comes up as Bosch part #00663802. This looks more like a power supply board than a relay board.

Should I replace the relay board?

Attached Thumbnails

   

via HBL5750UC/08 Bosch Wall Oven. Broiler element comes on / stays on in all cook modes.
by pfbzzz