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Thats not actually too bad. Cheaper than a ESL or EIS replacement.
I just bought a eurocharged handheld tuner the other week and if I end up having to get a new ECU I'm almost hesitant to flash the car with the tune simply because i dont want to potentially fry a new ECU. Although I am glad this did happen before tuning.
I have good news. Battery was the incorrect battery, a non AGM bosch unit, and had been slowly leaking acid underneath. Long story short, went and got the actual correct battery that I should have gotten and all is well. When I first checked battery voltage on thursday, it was with my battery charger showing healthy. I didnt have a voltmeter on hand and the cluster wasn't allowing access to read live voltage. Once I put a voltmeter on it last night it was 10.5volts. After an hour at a 2AMP charge, it went down to 9.7volts. I then removed the battery and saw all of the corrosion from the leakage.
Lesson here, triple check the battery when buying a mercedes that it is indeed a quality AGM unit, and if not, replace it immediately. I am hoping I dont have starter or alternator issues down the road.
FF. W212 E63 M156 non-pano 18" P2 ParkT NightV (gone but will be missed).
Man, that's quite a leak. Hopefully the leak has been mostly contained without dripping to other places. It's good to know you have sorted it out before going on a costly witch hunt at the dealership. Is the leakage from the main battery?
Originally Posted by 6speeddave
Main battery is 5 months old. OEM Auxiliary Battery replaced two weeks ago.
BTW, I didn't know there is an auxiliary battery. With regarding to the auxiliary battery: would you mind sharing some insights on where it is and what battery brand/model? Did you replace the auxiliary battery yourself? If yes, how difficult is it? How did you know the auxiliary battery needed replacement?
Yes, the leakage was from the main battery, which was not AGM, as those don't really leak. The acid dried before it could go far, however I wont know how far until I actually remove and replace it in a few weeks.
The auxiliary battery is below the instrument cluster above the footwell. Not horrible to get to but its kind of an awkward R&R. Your arm goes through the left side of the dash or from underneath near the pedals. I actually had both hands buried to do it.
The battery is OEM only, part no. 000000004039. Bought it from FCP Euro for $45 shipped around thanksgiving. The one I replaced was the original with a 2009 date, however I believe its still fine as its showing 12.2volts. Regardless, its replaced.
Symptoms were getting random lane assist failures once every other week or so for a split second. Little did I know it was due to my main battery being incorrect!
Hope this helps. Enjoy your holidays!
Last edited by 6speeddave; 12-19-2016 at 01:48 PM.
Thanks for the infos! Did the auxiliary battery tested bad when you swapped it out? Is the Auxiliary battery AGM, too?
The aux battery I pulled out still showed 12.2 volts and had the original date from 2009 on it meaning its probably never been replaced. I didnt actually check it with a load checker to see if it held the 12.2 volts though so I guess it could potentially be going back. The reason I replaced it though was because I was getting weird errors here and there....and little did I know it was due to the main battery, not the auxiliary.
12-16-2016, 06:49 PM
