I have an issue where my 2015 W205 C300 has intermittent trouble restarting from an ECO Stop. The dashboard lights come on and the car won't restart. I then have to push the KEYLESS-GO ON/OFF button to restart. The odd thing is it is intermittent, doesn't happen after every ECO stop. If ECO start/stop is turned off, it is not an issue however if you forget you could stall at a light unexpectedly while still in D. It never has an issue starting when I first enter the car or any issue manually restarting

I changed the starter last year after it failed. The auxiliary battery was changed 2 yrs ago, the main battery, battery sensor, and starter relay are new as well. I took it to the dealer for a Xentry scan and they did not find any codes. They thought the voltage dip limiter might be failing since this issue doesn't occur outside of the ECO Start / Stop process. The part which sits on the positive terminal was changed but the problem still persists. I already paid 2hr worth of diagnostics at the dealer without determining the underlying issue. Any thoughts on resolving this? I've attached a video to show what happens.

 

I'm just reading about the auxiliary transmission oil pump and its role. Has anyone seen that fail intermittently without any codes in Xentry or OBD? What would be the pattern of failure? Would it prevent the car from activating eco/start-stop in the first place or causing a failure on restart coming out of an ECO stop if fluid pressure is low? How does it overcome that if you manually stop and restart the car?

 

At this point I would pop the grey clip on the battery and disable the ECO start function. (search the forum for how to do that) This is a lot like the Covid shot, nobody is sure what the long term effects are going to be.
The other option is reprogramming the ECO function to normally off. The module is available online.

 

That would be the last-ditch solution but not sure how losing the battery sensor input may affect other systems. I would like to try and know the issue and see if it can be resolved. If it is ultimately too costly, then I can ignore it or disconnect the sensor as suggested. I'm not looking to use ECO start / stop but I want to make sure it isn't the start of some other issue that will lead the car to stall or have trouble starting later.

As an update, I got these code from OBD:
P1CE200 ECO Start / Stop has detected low engine speed
But I wonder if that is being thrown after the car fails to restart

 

The grey clip is for the battery sensor. Your alternator needs to know whether to charge at 10% or 100% if it only need little charge. Disabling the sensor will turn the alternator at 100% on all the time. On all the time instead of variable charging. It won't know when to stop even when the battery is full.

Good way to destroy your alternator and the battery. Mind you I ran it with the clip off for a whole year after finding the facts. Alternator and battery is ok but soon as warranty ends, I am sure I will need new ones.

 

let me read the tread to try and make an educated guess to help ya loose that problem.​​​​

My disclaimer here is I am really a W212 guy...

"Curious if you've seen this or have any thoughts? Starter,
main battery,
battery sensor,
fuses,
starter relay,
dip limiter are all new.
The auxiliary battery is about 2 yrs old.
Very frustrating issue."

Have you managed to observe the battery voltage/current during driving and EVO cycles?? You do that by calling the " secret maintenance menu" before starting the car each time - I believe you're likely to find your car charging then deep draining your battery while driving.

The weird thing is the ECO logic used to be smart enough to disable stop cycles with known discharged batteries.

dip limiter... is this a diesel engine?

The dealer charging two hours for zero result exemplify the need for this forum. Xentry can walk savy techs through troubleshooting trees. Let's see what we can figure...

Do you have a float charger... charge your batteries to full and see if this cures your ECO not restarting.

Let me know!

 

As an update, it is an intermittent starting issue which is most noticeably in the eco stop process since the car is unable to restart at a red light / when stopped. At times it does occur when 1 out 20 times when first starting the car, but another 2 clicks of keyless go usually start the car. It prob happens 5% of the time when trying to restart from ECO stop. It can be restarted by turning car on and off but It can even be dangerous on a hill, as when the car fails to restart, it will be in D and can roll down a hill unless you hit brake. It is odd because the computer should prevent any ECO stop and go yellow if there are any issues detected.

Despite this, the car will always restart manually or with another 2 clicks of the keyless go. Because it happens outside of eco start / stop it makes me think it is an electrical, sensor, or fuel pressure issue vs something intrinsic to the eco start/stop process. But because it also happens in the Eco start/stop process it is not a key/transponder, authentication or ignition, etc issue since the start signal is coming directly from ME control unit.

The only code in is P1CE200.

Similar to this: http://www.arfc.org/complaints/2015/.../11080871.aspx

 

do you own a scanner or only rely on what the dealer reported seeing? I dont want to rule out "Keyless-Go" is failing to communicate because it got disturbed by the goofy door modules.

Scanners deliver evidence to help along✌️

 

I have a scanner and there are no other codes popping up. It occurs even with using the key in the ignition.

 

good thing, we are crossing the T's to not ignore the obvious as much as possible 👍

At this point I propose to focus on voltage and battery charge activities. See above post #6 for guidance.

 

The voltage was one of the first things I looked at via the secret menu. I drove around with the menu and even caught the events on the video. The voltages never drop below 12.6v. Plus given that it happens and then the car can start instantly a second later, makes that the battery being weak less likely in my opinion.


The voltage dip limiter is in recent gas versions too and basically prevents a voltage drop when the car starts during eco stop so that the vehicle accessories / lights etc don't flicker/cut out temporarily during the starter activity. My understanding is there is a relay that adds resistance to the starter circuit to prevent a voltage drop.

The auxillary battery (voltage regulator / parking pawl capicitor) is part of the circuit on a W205 but when that fails there is a clear message on dashboard and ECO stop is prevented, so this behavior doesn't seem to fit. It was also replaced about 2-3 yrs ago. Unless it has some other failure pattern, I don't know about.

 

I think you got yourself a really interesting case !!
Charge never swings below 12.6v
keyless is not involvedboth batteries are in dependable stateNo reported DTC codestarts reliably otherwise...

I would question "drive authorization" and also read through existing TSB's fixes.

Ultimately XENTRY should have a related troubleshooting tree about that condition:
ECO FAILING RESTART but manual starts always successful.

--- TEST : Trigger an ECO RESTART by releasing driver seatbelt.
Have the car enter ECO OFF normally then unlock your seatbelt right away to see if this also fails to restart despite a really short OFF period.
​​​​​​​
​​​​To me this will definitely rull out "power issue" and classify that as a "logical issue".

 

TSB fixes are not exactly for this vehicle but other newer mercs with similar issues and 9-speed transmission. Mostly those involve software updates hence why I took it to the dealer but they stated all the software is up to date and couldn't find the issue. My understanding is that once the car is started, drive authorization shouldn't be an issue (warm start signal). So in the ECO start / stop process, drive authorization shouldn't be needed again to restart. I don't think xentry is that specific. It can diagnose starting issue or eco start / stop but those steps don't resolve the issue.

Tested with seat belt and even the actual eco start/stop button which are part of the same logical ECO Start / Stop circuit. It still tries and fails to restart with the same frequency ~1/20 as stepping on the gas which is triggers a start. So most of the times unbuckling seat belt or pushing button starts the car as it would coming out of an eco stop.

Are these logs helpful to anyone?

 

ECU SOFTWARE BUG...

 

I looked at this TSB but there are for diesel engine versions. That was the rationale behind taking to the dealer to see if there is a software update needed but they told me all the software is up to date. Is there a way to check this if you can get the control unit info to verify what they said? Like the latest firmware/drivers for computers?

They mentioned that they opened a PTSS case w/ Germany but got back that would need 6-15 hrs of diagnostics time with no assurance of a resolution or diagnosis. This is not practical / too costly for an out-of-warranty car. I already paid for them to do 5-6 hrs of diag but didn't get an accurate diagnosis so I was turned off at just throwing more money just to diagnose the issue. I wonder how much work they really did. I'm sure they wasted time checking tire threads, brake pad thickness, and other nonsense. I didn't get the sense they would truly help get to the bottom of it without spending 1-2k on diagnostics since it was out of warranty and they can't bill Mercedes. That was also before any repair on the car.

They also mentioned once on a PTSS case, they were told to change the engine or Germany needed to write a custom software update. I'm not sure this would again be practical for a 2015 car out of warranty. Also given that a lot of cars don't have this issue makes it seem that it is not a common occurrence which would be more likely if it is a software bug.

Here are some TSBs that are similar but again they are all software issues.

There is also this thread but it is in Dutch and can't get access.
https://www.amtgarageforum.nl/merced...top-46681.html

This thread is in Russian but I also didn't see a clear solution:
https://www.benzclub.ru/forum/showthread.php?t=371581

My real fear was this would turn into a progressively worse starting issue involving some engine sensor or fuel system that could leave you stuck somewhere but maybe the consolation is that it doesn't seem to be anything common and maybe not as serious.

Open to other ideas or thoughts? If you know anyone who can get to the bottom of it in the NY/NJ/CT area, I don't mind taking it. Just hate to get the runaround and getting treated like we don't know anything or wasting time/money on the things already tried/examined. When you mention ECO start/stop 99% of the time is spent on the reasons why ECO stop/start doesn't activate (yellow icon / no icon) rather than this issue of failure to restart/stall. In a way, that problem is easier to solve since there is a clear checklist in Xentry at needs to be met for it to be activated.

 

I know it's not the answer you're looking for... but for $200 you can get an ODB2 plug-in that either disables ECO or keeps it set the same way as your previous drive cycle.
I believe the quickest solution is to go through the Xentry troubleshooting to pin point your fix.

 

Been through the xentry steps which focus on electrical and fuel systems without an answer. The module doesn't solve the issue with it happening every now and then on initial startup too. I'd also like to fix it rather than mask it if possible in case it is an issue that gets progressively worse.

 

Hi, I am having the same issue on my 2015 C180 W205 M274. But ultimately it is getting worst. Since last week it fails to start every single time after been running for some time. I stopped at a red light and stayed there for over 10 minutes trying to restart by touching all buttons and switches until it starts again. No switches combination works other than waiting some time.
Any Help and or Ideas will be greatly appreciated.
PD: I already tried every single troubleshooting step mentioned in this tread without success.

 

Next step is to get service by MB dealer
Then ultimately post the fix here to help others.

 

I requested the dealer a Quote for the diagnostics. Hope it is reasonable.

 

Hope this works out well.

I'd let them fix it right when the Sce desk calls you.

🤞

 

Local Mercedes Benz agency quoted me $180.00 for diagnostics and a reparation quote. (No soo bad) but, Instead, I decided to request My mechanic to unmount the starter motor and I bring it to the Electro mechanic representative of BOSCH here in Panama, They didn't found anything wrong with the starter motor, but issue was appearing when the car was hot so I decided to request them replace the Solenoid. My Mechanic reinstalled the Starter motor and it is working without any failures since then. Electro mechanic labor $20.00 + Solenoid $20.00 + Mechanic labor $25.00 = $65.00 Intermittent issue repaired/fixed = Priceless

 

How did you resolve this issue

 

I am not a mechanic, but...

You can absolutely disconnect the state-of-charge clip without any worry. At least, I unclipped mine 5 years ago -- and I still have the same alternator and battery, both functioning beautifully. Having the clip attached allows the system to raise the charge level to 14. 9v when the battery is low, and also (maybe) lower the alternator's output when the battery's charge is above 80%, which helps (slightly) with fuel economy. I remember in monitoring it that there were two levels commonly used, 14.9v and 14.2v. Disconnecting it means the charging is like any AGM-battery vehicle without an exotic state-of-charge system -- the alternator puts out a constant 14.2v, which is considered ideal, and nothing gets overcharged. I don't remember ever seeing mine go below 14.2v. And I don't believe any modern charging systems involve stopping the alternator from charging altogether. Many modern cars just use a constant 14.2v.

Here's the thread about it. Certainly as a diagnostic step for a problem with Eco Start/Stop, it's a no-brainer.

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