Until i can get to a mechanic (thanks coronavirus). I am trying to self diagnose my car issues. when i am driving my VY Supercharged L67 the car will get up to normal temp, If i turn on any accessories (lights, wiper blades, stereo, fan etc) the temperature guage rapidly fluctuates between normal and cold temp. Then the check engine light sometimes comes on. I have noticed if i drive without any accessories on the temp stays at normal and the check engine light doesn't come on. I have just replaced the battery thinking that was the issue but it didn't fix it. Im wondering if it could be an alternator issue? any help will be much appreciated.