WARNING MESSAGE - Alternator Failure?
 

Got an interesting warning message last night on the dashboard of my 2015 C300 (W205): Icon of battery with an exclamation point (!) with the words "Stop Vehicle. Shift to 'P'. Leave Engine Running."

Same message popped up again today within about 5-10 minutes of driving. Couldn't really find anything on Google about the warning message other than a PDF document from a CLA Owners Manual, which said it means an overheating automatic transmission (?).

I pressed the Mbrace Vehicle Information button and the tech on the phone said it was probably an issue with the alternator, not transmission. He suggested I take it immediately to the dealership, which I did -- and of course, they've never seen the message on any of their vehicles before. They prepared me for a long wait while they do research to find someone who has knowledge of the message.

Has anyone had to deal with this message in any way with their C-Class?

- Mark


https://cimg1.ibsrv.net/gimg/www.mbw...0f2a99b62a.jpg

Charging and batt voltage problems are easy to diagnose. Your dealer should take care of this quickly. Most likely cause is probably a bad batt. It happens sometimes.

Tell them that you and the loaner car will wait elsewhere while they learn how to work on their car.

Turned out to be a loose battery cable. The warning looked ominous, but the fix was fairly simple. All good.

I just got the same warning for the first time on my 2015 c300.
Dealer said to let the engine run to 're-charge' the battery. Then to call MB roadside for support.

Can I easily tighten the battery cables myself?

The resting voltage on the battery got too low. Running the engine engages the alternator which restores the battery to full voltage. It can be a sign the battery is getting tired and not holding a charge, or the battery is being discharged by running in Accessory mode too long, or the cables are loose.

Remove the shield on the left side of the engine compartment, lift the air filter out of the way, and check/tighten the terminal connections. If they're already snug and the problem persists replace the battery.

i had the same message, pls advise what should i do? TIA

If you live in the U.S. and have a AAA membership or roadside assistance, they can test your battery for free.

I got the same error message sometime last fall and had to get a new battery.

I had the same problem with my S550 for a week. It sounds (reads) much worst than it is. The post was loose on the battery. Check there first, one of them is loose. Fixed the problem

I got this two days ago on my 2015 C300.
 

I got this two days ago on my 2015 C300. It was after running the car at Interstate speeds and parking it for a couple hours. It would not start, so how could I leave the engine running. Trying to start the engine wiped out all the icons that come on in the accessory position. Even the analogue clock (only Luxury trims have it) rewound itself back to 12:00. Various other warnings would come on.

I called MB Roadside Assistance. (Communications worked.) They said it would be an hour. After an hour, I went outside and tried it before I followed up. It started! No further problems since then -- ??

I had this after the car was parked in the sun half a day. Go the message after 200m driving, turned it off and.on again so I drove home and on arrival again the message. Put the car inside and turned it off. Since then I havent had the message returning. Strange ****

A good explanation of this problem can be found here.

Hi,
I am sure it is auxiliary battery to blame, you can check this blog for more information https://xenons4u.co.uk/blog/mercedes...ode-explained/

Yes I have C-300 Mercedes Benz 2015 with the same problem. The secret lies in the battery. Just disconnect the negative cable and reconnect after 2-3 minutes and magic this message is gone. Good luck and be happy to save money.

Just disconnect negative battery cable and connect it again after 2-3 minutes. Good luck.

Might as well check the positive terminal for tightness while you are playing with the battery.

I hv got the 'battery image !" icon together with a humming noise
 

I hv got the same "battery icon !" image in Dec' 2018, and took it to the dealer and proceeded to change with a new battery.
​​​A week ago, the "battery icon !" image re-appeared again, and together with it was a medium pitch humming noise from the engine. This time around, the dealer had stated that the alternator was defective and require to be replaced with a new.
To date, my C200 W205 had it's batteries changed twice, and now requiring a new alternator after using it for about than 4 years 6 months with mileage clocked about 60,500 km.

I've had this warning sign for the last 8 months.
When I took it to an auto shop and had them to battery health test, they said the battery was in good condition and that I should drive the car for half an hour +.
I rarely drive this car and assumed that a dash cam with a parking mode was draining the battery.

The other day I drove for 10+ hours and while the message disappeared for a day or so, it came back on.
When I had my car serviced at a dealer recently, they asked me if I wanted them to diagnose the problem. They had no idea how long that would take, so I said never mind and drove off.
The message went away if I drove an hour before but nowadays it just doesn't go away after driving 2 hours.

Does anyone know a part number for the alternator? Do dealers usually charge you for just diagnosing this sort of issue?

I had the same warning 2 months ago, it popped up and go away randomly. I took it to the dealer and they replaced the main battery under warranty. I was pleasantly surprised because I thought battery was a wear and tear item similar to brakes but my service advisor said it is covered under the oem car warranty. Saved myself a few hundred dollars I am sure :)