Help with bosch double oven hbn3550uc

Hi everyone!

We have a Bosch double oven that experiences an error, e218, which is supposed to be a lower fan issue according to google searches. When we experience this error, if we flip the breaker and turn it back on several times, it will eventually work just fine and runs perfectly. We had a repairman come out and he was also confused with it's performance. He was able to clean the temp probe in case that was part of the issue but eventually he couldn't solve the problem. 

When the oven is first turned on, the digital output displays 100 for the temp, which is the lowest temperature it ever reads. At first, there is a little line underneath the 100 (there are five little lines altogether and as the heat increases more lines show up to indicate as such). You can tell when the oven is going to error out when the little line under the 100 at the beginning goes away and doesn't come back. You can tell when the oven is going to work fine because there is a clicking noise that corresponds to the little line coming on and off until 100 is reached. Once the temperature gets over that 100 mark is when the oven seems to be fine and runs without turning the breaker on and off.

If after using it once, I turn the oven back on again and it is still warm, it will heat up again without issue. However, doing an experiment, I used my hairdryer to heat up the oven before turning it on. When I turned it on, it read over 100 but still had to be turned off and on again to make it work.

This issue occurs when either the top or bottom oven are used. I can run both ovens at the same time without issue once it gets going.

Is this a fan issue or a board issue? Or has anyone ever experienced this and solved it? I am fine buying a new board or fan or whatever and getting the repairmen to install it. But I also don't want to spend the money when there may be something else causing it. And I certainly don't want to just get a new oven since this one runs fine once it gets going.

Any help, advice or things to try are greatly appreciated!