Hi -

I am not an experienced car guru, but it seems as if you guys are so fingers crossed my post makes sense. I have a sporadic issue with starting my 2014 GLK. I am having trouble getting the auto shop to diagnose, because they cannot duplicate the issue, since it starts up fine when they try it. The "symptoms" are as followed, and I am not sure if they are all related or not. I was hoping someone here could give me an idea of what to ask the mechanics to check. The Mercedes dealership is almost an hour away, so I am hoping I can avoid taking it there just for diagnostics.

1. First, ECO mode stopped working. I noticed one day that my engine never cuts off at red lights or in drive-throughs anymore; however, the ECO light is still on.
2. About a month ago, every so often the car would start fine, but not switch into Drive or Reverse. After a few tries, it would finally switch. Sometimes I would need to turn the car off and back on to get it to do so.
3. Now, the car sometimes will not turn over. It cranks for half a second and then abruptly stops. The lights, wipers, radio, etc. all work fine during this. Usually after a few minutes and a few tries I can get it to start. Other times, the car turns over perfectly fine. The auto shop cranked it 20 times, and it started strong every time. For example: car started great all day yesterday and this morning, but took about 20 minutes to start at lunch today.
4. Other random, but single, occurrences have been:
Once last week my car reverse camera stayed on, even when I went into Drive.
Once in the last month my radio randomly powered off about one minute after I started driving.

Anyone have any thoughts??? I would be forever grateful for any ideas! Thank you!

 

Have your battery checked, a failing battery can cause these problems.

 

Thanks @karmikan ! They said they thought my battery was good since it started so “strongly” all of the other times, but I will have them revisit!

 

You have two batteries , one in the rear for auto start. If your in a cold climate you need starting power when it gets colder , your battery is old, you just need a quality AGM battery you can get anywhere . By the time you get to MB your battery is charged up. You could put a simple volt meter on it before you start to see it’s resting voltage , most any auto parts store will test it for free. Yes most of what you describe could be a weak battery.

 

Thanks @Mmr1 Should I be checking the front battery, back battery, or both?

 

Did you buy it new? So you know it hasn’t gotten into water? How many miles? If it’s been cared for , I would get a new AGM battery . I think the rear battery will have a dash warming when it goes bad, if you use stop start a lot then it’s worn out. I never use stop start because you loose oil pressure.

 

DId you ever get it working properly?