I have a Thermador SGCS365RS cooktop. The issue is with the front right burner. When cold, it ignites and operates ok. After buning for a while (5-10 minutes?), the flame stops. The igniters continuously attempt to re-ignite it. There is no gas - I have checked with a match. The operation is the same whether in the normal mode or the extra low flame mode. After the burner cools sufficiently, it will again ignite ok and burn until it warms up again.

Tom, you're thinking this uses a thermocouple to keep the valve open, when it's actually the simmer control module which sends 110vdc to the solenoid valve whenever the flame should be on.

Jim, I would say your solenoid valve is overheating and closing. You can confirm this by measuring 110vdc at the solenoid when this happens, though it may be a major PITA to do this. If you would like to order the solenoid, it's Thermador part number is 411253.

KC