unprocessed

Had had my C300 for almost a week and over the last two days I've commuted to and from work, my stop/start has not been working. I have a lot of stop and go traffic, and at a full stop the engine stays on. The system worked just fine earlier this week.

Any ideas on what the problem could be?

PeterUbers

Does it turn green? Or stay yellow?

If Eco light not even on, there may be a fault code thrown with Eco system

I had a bad crankshaft position sensor

unprocessed

The light is green.

cidtek

Mine hasn't worked for a while either. Today with a fully warmed up engine sitting in a car wash line it never shut off.

PeterUbers

Does the green Eco come on the dash and the engine still doesn't stop?

Then you have a defective system and need diagnostics

unprocessed

The green eco indicator on the dash doesn't come up now (when the car stops). It did when it was actually working.

PeterUbers

So it stays yellow?

unprocessed

A little confused on what you're referring to.

cidtek

And I also have a green light.

PeterUbers

The Eco button on the center console has a green light that you can toggle on and off

I am not talking about this

I am talking about the dash info cluster right in front of the driver... You... Does it say ECO in green when you are at a stop?

unprocessed

It does not, however it would be green at a stop when it was working a few days ago.

PeterUbers

Ah ok

Basically it may not be meeting the many variables that need to be active in order for it to stop the engine

It may possibly still be working ok, just not finding all the variables to be active in order to shut off

Take it in, see if Benz says differently

miketc

What I found is that the car needs to be warmed before stop/start is activated. Was the car warmed up?

djdj

Among other things, Eco Start/Stop won't work if the battery is not adequately charged or the engine temperature is not high enough.

oachim

You should read owner manual as it explains quite in details the conditions needed for the Eco to work / activate ... The system is having a lot of variables ...

If you consider it should be enabled and it does not work, I would suggest you check for some days and then report issue to the dealer.

I had a similar problem on my w204 after 1 year - solution was replacing the aux battery

Amo

unprocessed

Thanks.

A few big variables:

• The outside temperature is within the range that is suitable for the system.
• The set temperature for the vehicle interior has been reached.

Since I've been driving when it's 5 degrees out and with the heat on, now I can see why the start/stop hasn't been working.

coladin

I know what you are talking about, we do not have an ECO light like the E Class does.

C300Ross

Mine hasn't worked for over a week. Then again, its been around 0-10 degrees outside every day I drive to and from work. I just figured it was too much strain on the system to start/stop in these frigid temps. I figured if it didn't work when it's 50 degrees again, maybe I have an issue.

dnice-1

I wish my start stop would stop working! It gets pretty annoying in stop and go traffic where I end up disengaging it all together

miketc

No wish is needed, leave it off and it'll stop working.

socal400

I had a similar problem, another variable is if the A/C is on, ECO doesnt activate for obvious reasons. I prefer to have it off permanently when possible...

PeteInGilroy

I've learned that if you have a light foot on the brake, stop-start doesn't engage. Press the pedal a little harder and the engine shuts off.

If you press the pedal too hard and the engine shuts off, let up on the brake pedal, keeping it pressed just enough to keep you stopped.

dnice-1

FYI. I find the start stop still activates even with the AC on. I've also tried the light brake pedal trick to no avail

Jchungster

I was experiencing the same thing and when I took it in they just explained that there were a lot of conditions that all have to be met before the Eco stop/start will activate. Turns out nothing was wrong and when it got a little warmer, it started doing it more often. I was just being paranoid and you may be too .

smudge

I've the same issue in my C300 Hybrid, I'm totally disappointed with it, it completely breaks the hybrid function

Have contacted the dealer, they have done a lot of tests and found "no problems".

Maybe to cold for it right now, let's see if it improves as the spring begins.

If anyone has an hint please share.