Mespo

Hello all,

I own a C300 W205 MY2018…

I am wondering if one of you did experienced the following.

It happens two (2) times on the last month (hot temperature outside).

First time: ECO START / STOP enable, stop at a traffic light by pressing the brake pedal, the engine stop because of ECO Start / Stop, still pressing the brake pedal because the light is still red but the engine restart by himself (like I release the brake pedal)

At the second light, this time, just after releasing the brake pedal which should restart the engine…ALL the lights in the dash light up and the engine is completely OFF…I do need to press the button to put the car in Park press and restart the engine by pressing the start button.

Second time: Same pattern…it doesn’t look like it’s dangerous but people behind me getting frustrated ;-) Of course it does not happen if I disable the ECO START / STOP which I did these last days...

I will go visit Mercedes Benz dealer tomorrow…but I would like your input before doing so!

Best regards,

Andy74

I wish our friends the Germans gave us the option to permanently disable this frustrating eco start then stop then start. Everytime i turn on the car i have to disable it.

MBenzOwner

I have the issue for about a year. See this thread:

https://mbworld.org/forums/c-class-w...-stalling.html

I have taken to dealer and unfortunately they couldn't figure it out. They wanted many hours of diagnostic labor to figure it out as a PTSS case but it is out of warranty. I've tried a bunch of things listed in the post. Next step would be spark plugs and crankshaft position sensor but it could be a software issue which I thought dealer would have found. Curious to know what your dealer finds? Is it under warranty?

Mespo

Good morning MBenzOwner,

MBenzOwner -this is (video) exactly what happen to me twice on the last month.
My car is still under warranty, until the end of july. I am having an appointment at the dealer tomorrow for an inspection before the warranty end...
It's scarry reading your story...since that your dealer did not found anything on your car...did it happen recently?
I am guessiing that like me you disable the ECO Start / Stop when you drive?

I will keep you inform after my visit at the dealer at least I can show your video...thank you very much for you input!

Best regards,

MBenzOwner

Definitely get it checked out before the warranty ends. How many miles do you have? Mine is 2015 C300 RWD with 100K miles.
There are a few NHTSA reports of it online too without a resolution.

It started about a year ago. I also had the P052E code so I thought it was related. I had that code fixed/go away with the crankcase breather assembly replacement. It is common and all over the forums. It was a big job. They also replaced the starter and main battery at that time but this intermittent restarting / stalling issue didn't go away. I figured let me drive for a bit and see if it goes away. It persisted and the car didn't give me any new issues, so then I attempted to spend more money and fix this intermittent starting issue. Starter relay, fuses, engine grounding, auxiliary battery, battery sensor, voltage dip regulator were all changed without solving the issue. Did all the xentry tests of the electrical and fuel system without solving the issue. That's why it could be a software issue.

The car works fine otherwise. Have to remember to turn off ECO start/stop when you get into the car because it does automatically turn on when you start the car.

I was worried it could be a harbinger of future starting problems so I still want to fix it but the dealer couldn't solve it. In the end, they opened a PTSS case with Germany but they wanted 7-10 hrs of labor diagnosis on top of the money I already spent with them. That was before any repair and they said Germany might say replace the engine or something outrageous so It just didn't make financial sense to spend money on just diagnostics. I am eager to resolve it / prevent it from getting worse, so let me know what your dealer says. My other ideas were to change spark plugs and the crankshaft position sensor but if they can solve it, maybe I can take it to him or do what they end up doing Once the warranty expires, Mercedes won't care to really help you.

Mespo

Hello all,

Just for your information...I just had a call with the dealership regarding my annual check and the behavior with ECO START / STOP.

The answer from the technical advisor was that I don't ride enough my car he said...usually car should run between 10k - 20k /year so the alternator can recharge the battery properly :-/ and he want to charge me for the diagnostic / recharge which I refuse since the car is still under warranty.

My point of view is...I don't believe them...come on I can understand that the car is MY2018 with only 42,xxxkm (26,xxxmi), I am using it every day to go to work (12km round trip) but dealership ARE dealership ALWAYS want mor money from you.

At the end I had to pay $863.00 CAD for Service A, change of whiper blades and change brake fluid.

To be continued...I will leave the ECO START / STOP to see if by recharging the battery fix my problem.

Be safe....and best regards to all!

stockbmw

Thats stealership right there. I had my battery warrantied when eco stop no longer worked, and my round trip is shorter then yours 5 kms. No diagnostic fee or recharge fee. It would have been cheaper if you PAID for new battery and spend $10 on installation and bought battery maintainer, and that would have fixed your problem.

Expensive oil change my friend.

MBenzOwner

Dealer brushed you aside. If the battery is low, eco start / stop would not be activated. The eco light would be yellow.

If the car stalls / fail to restart like that is a different issue. At least you have it documented so if it happens in the next few weeks they should fix it under warranty. Definitely get it resolved before warranty expires.

DasPoot

Yes it causes a myriad of issuof. Poorly implemented with Hyundai parts.

Just unplug it. It caused all sorts of transmission issues with mine until i un-Hyundai-ed my Benz.

CaliBenzDriver

You to try to sort out if it is due to a low battery voltage after 30 second draining at traffic light,-Or it is a logical fault like Drive Authorisation System.

Most important now as you noted, it dies in traffic... don't let that car kill you by surprise. Remember to disable stupid the ECO (Engine Cut Off) function.

Try to float your battery with a CTEK charger and see if it radically fixes your "ECO NO Restart".
Additionally you can try a quick-cure-all: unplug your batteries for 10mn.

​​​​​​Our car struggles are farmed to extract amazing profits.
🤗

Andy74

Ok how to unplug it?

mikec35

A weak battery can cause all kinds of issues with these cars. I'd try charging the battery and see if that helps. You could buy a battery load tester and check the battery with it, it'll tell you if the battery needs to be replaced. Although not the same issue, my eco start quit working because my battery was weak. I bought a relatively cheap load tester and it told me the battery needed to be replaced. I replaced it and it's worked fine ever since.

mikec35

This is the battery tester I bought. I have so many batteries, 4 boat batteries, 2 jet ski batteries, 6 car batteries, 2 motorcycle batteries, 2 mower and 1 ATV. It was worth the $58.99 (it's 20% off right now) price tag for me to buy this battery load tester.