Active Calories too high

Does your HR graph look correct?  It didn't measure too high for any reason? Secondly, your title says active calories.  Is the 545 the actual active calories for this walk, or is this the total amount for this walk?

Yes the hr ist correct. I started the activity walk( in german gehen) and the 545 ist the Total amount for the walk. 

So, when you programed your watch you entered your age, sex, height, weight and activity level and Garmin calculated your BMR. If you look at your calorie widget in Garmin Connect Mobile for the previous day, this will be listed as resting calories. As long as you haven't changed any of those recently, they'll be the same every day.  Divide that number by 24 and that's what Garmin has you burning hourly just to sustain life (breathing, your heart beat, etc).  For simplicity, let's say yours is 2400 cals a day, or 100 an hour.  If this were the case, an 1 1/2 hr walk would burn 150 calories in addition to your activity. 545 - 150 =  295.  So, 545 for the duration of your walk, 150 of that was from BMR and 295 from the workout. Does this line up a little better with your BMR and make sense? 

Yes i programmed the watch and i am about 2200 per day. 

That Would be 545 - 137,5 = 407,5. And 407,5 is mich too high for a walk with my kid. I mean it took about 25 min for 1 km which is very very slow. 

My wife has an Apple watch and she had about 150 extra cal for the walk.

Well, I didn't say I agree with Garmin's calculations, I just know how they calculate. :). Do you feel 2200 is correct?  If that's off, you can adjust the activity class in Garmin Connect and this changes your daily BMR.  If it is correct, I'm not sure what to tell you.  Also, make sure your resting and MaxHR are correct as I believe this may factor in also, but I don't know for sure. 

Unknown said:

That Would be 545 - 137,5 = 407,5. And 407,5 is mich too high for a walk with my kid. I mean it took about 25 min for 1 km which is very very slow. 

The pace is irrelevant. What counts is your heart rate, and the HR Variability. Please post the HR graph of that Activity and the Stress graph for given day - it may gives us some hints why the Calories were higher than what you expected. 

Once every few weeks my energy level starts to read way too high. Once I notice it I just turn the watch off for half an hour and the problem is fixed.

Unknown said:

Once every few weeks my energy level starts to read way too high

It would be still interesting to see the HR and Stress graphs for that time period. Possibly the HRM got out of sync and started measuring either high HR or low HRV (low HR Variabiity = high stress). Or they were really high at that moment, and in the half an hour, they settled down.