My oven recently started to fail to reach baking temperature or hold it. Never gets past "Preheat" on the display.

I tested the temp sensor (thermocouple) - tested good, but replaced anyway with a new part. No change.

I replaced the controller board. No change.

I tested the baking element - tested good, but replaced anyway with a new part. No change.

Tested the 240V line at receptacle and at cord. Tested good.

Broil element heats. Broil cycle works.

Convection element heats. Convection Broil works, but not Convection Bake.

There is no fuse in this oven.

Suggestions?

I replaced what you call the relay control board, which Bosch calls the power module, 00657860. It is the main controller for the oven. The display works fine, by the way, and shows no error codes.

Hi.

If there is no hi-limit thermostat inline with the bake element circuitry and you already replaced the relay board, the sensor and the bake element you should test the wire harness and replace the display board.

Here is the display board Part number: AP5263087

Hi.

If there is no hi-limit thermostat inline with the bake element circuitry and you already replaced the relay board, the sensor and the bake element you should test the wire harness and replace the display board.
Check this manual, it's seams to be helpful: http://www.atechappliancetechni...__HDS__HEI__HES__HGS.pdf

Good luck. Please keep us posted with the results.

Thank you,

Simon.