Oven over heating , from set temp of 375 to over, third time the

The default for most Miele oven is 375 - however this is an earlier model oven that only allowed (as yo said) ten degree increments - I am afraid that there is no solution to that.
370 or 380 would be your options

Need to know if it's gas or electric and model and serial # if possible. Thanks

Most likely you have a bad thermostat.
Oven repair in Mission Viejo, CA
Appliance repair in Mission Viejo and Orange County, CA

Sorry to read about your problem, I hope this helps you out.

you have a defective temp probe or heat control knob

I tried to help you. Please help me and Rate/Vote on my response, thanks and good luck

If you are monitoring the oven temperature with an analog style thermometer you may actually be ok, but seeing the thermometers slow reaction time.
Some newer ovens actually do pre-heat beep prior to reaching temp in an effort to conserve eelectricity.
A good home test is to try your oven at several different temps to see if there is any variation in internal temperature. Try it one day on 300, the next at 375 and another day at 450. Give your analog style thermometer time to catch up (usually just about 15 min) and leave it on for a half an hour to see if the temp maintains.
Also Beware of aluminum foil AND THE NEW OVEN LINER MATS as they can alter oven performance bay absorbing and blocking the ovens natural heat radiation and convection air flow currents that happen in all ovens, not just convection models.
Another interesting fact is that older ovens used a thermostat in them that operated much like your thermometer and was very slow to react making the oven typically about 100 degrees hotter than where the customer set it. This was just a fact of life before the advent of electronic temperature management and became noticeable when people began trying to bake older "hand me down" recipes in the newer ovens with less than stellar results.
You can mimic the older oven performance by preheating the oven about a hundred degrees higher than called for and after it reaches temp, re-set it to the correct temperature and put the items in right away.
If you find your temperatures fluctuating ask your servicer to replace first the temp sensor and as a last resort the control board as this part is usually pretty expensive.
Good Luck with this!

You need a new t-stat on this unit/ YOu can call us with the brand and model number and we can get the proper parts for you. Hope this helps you out! Thanks, Ella!~ :>)

Probably a bad oven temperature sensor.

if you cant program it for more than the 270 you may have changed it from farienhiet ( bad spelling) to celcius. pushing and holding broil may switch it back.

no there is not and your unit only has one temp sensor you will have to spring for a new control

Yes you do need a new thermostat, just make sure that the sensor is not obstructed by anything. first.
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Thanks.