I have a similar problem with my Bosch HBL645, though mine seems to be off the same amount at various settings (which leaves me with the option of not repairing). Mine also cannot be calibrated. I was told that replacing the termostat (at about $385) was the only solution.

Attention KRISZ!
My brand new F&P double oven had to have both fans replaced because of the noise, now neither oven will preheat or heat up to temperature. Krisz, what did they replace on your oven to fix your preheating problem?
Does anyone else know what might be wrong?

boy, guys, I don't have a F&P oven, but I'm not so sure that there would be a problem. Temperature fluctuates over time within an oven, every oven. There is no single degree that an oven stays at all the time. Ovens heat up and then they cool down. To get the most stable temperature an oven has to be preheated so that all the metal elements are at approximately the same temperature as your target. This takes at least thirty minutes and no earlier, from what I've read on the board here. I don't know that I would be worrying too much about a ten degree difference at all.

Anyways, I've also gone back to using an analog thermometer because digital thermometers keep me watching too closely in my ovens. Warm up cycle, I can see a 25-50 degree difference. Once my oven is warm, the fluctuations around the middle shelf really aren't that significant. When you open the door, it will take any oven 5-10 minutes to recover temperature.

I've also come to believe that a lot of recipes don't have their times right for the approximate temperatures. Just read different recipes for the same type of cookie.

But again, using an analog thermometer gave me the chill pill I needed.

Preheat your oven at least 30 minutes.
The middle rack is going to have the median temp. High rack will be hotter, low rack will be much lower.
Expect heating & cooling cycles.
Watch your food cook - not all recipes gauge the cooking times accurately.

Sorry I can't help with a noisy fan or anything.

best wishes,
-a

cfulton, I am sorry that I am just now reading your message. Do you still want to know? I think replacing the oven sensor took care of that. Andrea, I do know that oven temps fluctuate and that it takes time to preheat. But I still have a problem.

Just thought I should probably say that my oven is fixed.
It was something to do with the self cleaning element. The company paid for it, and the oven is working fine.

I have a problem with the oven fan starting by itself even with fan switch in the off position. F&P customer service tells me this is to keep the control panel cool.
Then why have a switch? Sounds like a fish story to me.

Krisz, I am having some major struggles with my fisher Paykel oven. How did you convince them to get you a new temperature sensor?

I didn't have to convince them. When told the issue, the company just sent the part.