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So I have a e63s, and my eco start stop hasn’t been functioning in a while. My cylinder deactivation works, but just not the engine deactivation during a stop. I usually travel to work in this vehicle and there’s currently construction so I would really appreciate the engine deactivation to work because of the long stops.
my car currently has just under half a tank of fuel (45%). I had a minor warning for my 12V battery saying it’s too low and i need to drive my vehicle a bit to charge it. I did it and now the message doesn’t appear. I don’t know whether it was the auxiliary or the main battery, and nor do I want to pay 350+ tax to find out.
I usually just have my massaging seats on, ventilated or heated, but rarely do I turn on the A/C. Also the engine is at operating temp.
On the unlikely chance that you haven't noticed it, my 2018 E400 has a button on the console for activating and deactivating the start-stop function. When it's on, the button lights up.
Last edited by The_Judge; Jul 26, 2025 at 11:57 AM.
Reason: spelling error
OP, do you also shut down the plane's engines when you're waiting in a holding pattern?
But seriously, why do people think the start/stop is a good idea? Don't get me wrong, if you like it, I'm not knocking it. Just curious. You're adding more wear and tear on the engine and starter, more wear on the battery / batteries and for what? In the quest of saving a couple of cents in fuel? The only reason Start / Stop is there is to help manufacturers meet CAFE fuel economy standards. At leas tin the US. In the EU it's mandatory.
OP, do you also shut down the plane's engines when you're waiting in a holding pattern?
But seriously, why do people think the start/stop is a good idea? Don't get me wrong, if you like it, I'm not knocking it. Just curious. You're adding more wear and tear on the engine and starter, more wear on the battery / batteries and for what? In the quest of saving a couple of cents in fuel? The only reason Start / Stop is there is to help manufacturers meet CAFE fuel economy standards. At leas tin the US. In the EU it's mandatory.
Couldn't agree more! Shortly after I bought my 2018 E400 and experienced the start-stop "feature" for the first time, I went to EBay and found a device that changes the default setting for on-off to off. I could still activate on-off if I wanted to, but that ain't gonna happen.
BTW, I recently had some service done on the car that required the installation of two software updates, and that resulted in changing the default setting for on-off back to on. So I plugged the device back in, ran the very simple installation process once again, and the default is now back to "off."
I’m only trying to fix it because of the construction they are doing. They closed lanes and I sit in traffic and my car just eats through its tank. MB told me it’s my auxiliary battery that manages the start stop eco. They quoted me for $420 just for the battery. I found the same thing on Amazon for like 50$.
That engine will go through no more than .5 gallons of fuel per hour when idling. I'm willing to bet it's less than .5 gallons per hour, even.
But I get it, with gasoline being so scarce post The Apocalypse and all... wait, that hasn't happened yet?
Seriously, though. You're saving a few pennies now, at the expense of dollars later on. But, if you don't plan on keeping the car for a long time, this may work better for you and save you a few hundred dollars over the course of a few years.
OP, if you are still on the original 12V battery, then the battery is likely at the end of its rope and you need a new main battery. The aux battery isn't actually a battery. It's a capacitor module. It's very easy to replace. I did it for good measure on my 2019 C63 after I had the main battery replaced, and looks like the W213 uses the same module. It's behind the passenger footwell. You do have to get the right tools and the first time it takes a bit of time to figure out how to get everything opened up. The part is around $120. You can find YouTube videos for how to replace it. I used the one below. It's for the W205, but I believe it's pretty much the same for the W213.
An old dying battery is likely why your start/stop isn't working anymore. It's one of the first telltales that the battery needs to be replaced. Having said that, you know you can always turn off the engine manually if you are stopped for a while? Start/stop on these cars doesn't keep the engine off very long. I basically disable it like others above as it frequently kicks the engine back in after only a few seconds. It's a silly "feature" on these cars. Since you are not using AC, it might keep the engine off longer as it doesn't have to maintain the cabin temperature, but then you might as well just shut the engine off manually if you are stuck at a construction site for a long time.
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by Sathinas
OP, do you also shut down the plane's engines when you're waiting in a holding pattern?
But seriously, why do people think the start/stop is a good idea? Don't get me wrong, if you like it, I'm not knocking it. Just curious. You're adding more wear and tear on the engine and starter, more wear on the battery / batteries and for what? In the quest of saving a couple of cents in fuel? The only reason Start / Stop is there is to help manufacturers meet CAFE fuel economy standards. At leas tin the US. In the EU it's mandatory.
The start/start also helps with air pollution. Sitting at stop light for 60/90 seconds with the engine idling vs. with the engine off. I personally like it for the environment - it is small but every little bit helps.
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by superswiss
OP, if you are still on the original 12V battery, then the battery is likely at the end of its rope and you need a new main battery. The aux battery isn't actually a battery. It's a capacitor module. It's very easy to replace. I did it for good measure on my 2019 C63 after I had the main battery replaced, and looks like the W213 uses the same module. It's behind the passenger footwell. You do have to get the right tools and the first time it takes a bit of time to figure out how to get everything opened up. The part is around $120. You can find YouTube videos for how to replace it. I used the one below. It's for the W205, but I believe it's pretty much the same for the W213.
An old dying battery is likely why your start/stop isn't working anymore. It's one of the first telltales that the battery needs to be replaced. Having said that, you know you can always turn off the engine manually if you are stopped for a while? Start/stop on these cars doesn't keep the engine off very long. I basically disable it like others above as it frequently kicks the engine back in after only a few seconds. It's a silly "feature" on these cars. Since you are not using AC, it might keep the engine off longer as it doesn't have to maintain the cabin temperature, but then you might as well just shut the engine off manually if you are stuck at a construction site for a long time.
Another way to test, which is what I do is to put a charger on the batter and fully charge the battery. I usually do this 2 or 3 times a year - I am still on the original batter on my 2019 E450.
I then go to "standby mode" and see how many weeks are left. For me it is usually between 28 and 32. Then a few weeks later I once again go to "standby mode" - not having charged the battery but after normal use. The weeks left often drop to 22 to 24, less but still almost 6 months, which to me indicates my battery is still good.
My '18 E300 factory setting is defaulted to off. When trying the setting, I found that Eco Start/Stop function self disables when the A/C is running which in Florida is 10 months or more per year.
I appreciate all of your concerns with the start stop eco. I live in Canada and 94 costs just around 2$ for every liter. Coming to just under 8$ a gallon in US terms. My vehicle has been giving me some little warnings about the auxiliary battery and I figured both batteries need replacing since it’s 2018 and I haven’t changed the batteries. It was concerning that stop start would just stop functioning. I don’t want to manually turn off my vehicle but sometimes Iv had to do it. Trust me when you sit in traffic for 30 min and your still not across town, it kind of hurts.
especially with the fact that Mercedes wants to charge me just over $900 for both batteries without labor + tax. I just had an o ring replaced, a sensor, and a fuel line replaced, Iv spent way too much on this car in 3 weeks and I’m just a uni student. I make decent money, but not that much to be able to spend over 3k on repairs every month.
Last edited by Whatmypilot; Jul 26, 2025 at 03:32 PM.
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by ua549
My '18 E300 factory setting is defaulted to off. When trying the setting, I found that Eco Start/Stop function self disables when the A/C is running which in Florida is 10 months or more per year.
Interesting: on my 2010 E450, the Auto/stop default is On, regardless if the AC is on or off.
Maybe because you have the E350, 4 cylinder, the engine even with auto/stop "on" the engine always is on with the AC on. With the E450 with the AC on, the auto/stop engages and the engine does turn off - albeit usually not for more than 30 seconds.
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by Whatmypilot
I appreciate all of your concerns with the start stop eco. I live in Canada and 94 costs just around 2$ for every liter. Coming to just under 8$ a gallon in US terms. My vehicle has been giving me some little warnings about the auxiliary battery and I figured both batteries need replacing since it’s 2018 and I haven’t changed the batteries. It was concerning that stop start would just stop functioning. I don’t want to manually turn off my vehicle but sometimes Iv had to do it. Trust me when you sit in traffic for 30 min and your still not across town, it kind of hurts.
especially with the fact that Mercedes wants to charge me just over $900 for both batteries without labor + tax. I just had an o ring replaced, a sensor, and a fuel line replaced, Iv spent way too much on this car in 3 weeks and I’m just a uni student. I make decent money, but not that much to be able to spend over 3k on repairs every month.
Just a suggestion and certainly not for everyone: Walmart will install a new battery with a 4 year warranty for US $179. If you decide to go this route, remember to remove the cover to the battery before having the battery replaced.
I watched them install a battery in my Ford Edge Sport (now ST) and the technician did an excellent job. Just ask for the foreman to do the installation. I also tipped him - and from the look on his face, it may have been the first tip he ever received!
The start/start also helps with air pollution. Sitting at stop light for 60/90 seconds with the engine idling vs. with the engine off. I personally like it for the environment - it is small but every little bit helps.
I can appreciate your attempt at "helping" the environment, and I would like to thank you on behalf of the rest of use who think that stupid Start / Stop "feature" is nothing more than a bad joke, and don't use it.
I appreciate all of your concerns with the start stop eco. I live in Canada and 94 costs just around 2$ for every liter. Coming to just under 8$ a gallon in US terms. My vehicle has been giving me some little warnings about the auxiliary battery and I figured both batteries need replacing since it’s 2018 and I haven’t changed the batteries. It was concerning that stop start would just stop functioning. I don’t want to manually turn off my vehicle but sometimes Iv had to do it. Trust me when you sit in traffic for 30 min and your still not across town, it kind of hurts.
especially with the fact that Mercedes wants to charge me just over $900 for both batteries without labor + tax. I just had an o ring replaced, a sensor, and a fuel line replaced, Iv spent way too much on this car in 3 weeks and I’m just a uni student. I make decent money, but not that much to be able to spend over 3k on repairs every month.
Probably not a smart choice of car in that situation. While $900 seems highway robbery, if you are worried about the cost of gas, commuting in a V8 is the last thing you should be doing. Just saying. These are not commuter cars by a long shot and pretty expensive to repair. Just wait until your rear main seal starts leaking. My theory behind that is that lots of stop & go traffic isn't making these engines happy. FWIW, I paid under $500 US to have my battery replaced, including labor, and then another $120 and about 30 minutes of my own time to do the aux battery.
Last edited by superswiss; Jul 26, 2025 at 04:21 PM.
I tried using start/stop eco when I first got my car. I stopped using it soon after when the car shut down while I making a left turn and didn't start when I took my foot off the brake to complete the turn.
With my 2018 wagon, I found that the eco function stopped working once the main battery in the engine compartment fell below a certain voltage output (don't remember which). I put a battery tender on it at night and the eco function worked again in the morning. The long term solution was to replace the battery.
OP, do you also shut down the plane's engines when you're waiting in a holding pattern?
But seriously, why do people think the start/stop is a good idea? Don't get me wrong, if you like it, I'm not knocking it. Just curious. You're adding more wear and tear on the engine and starter, more wear on the battery / batteries and for what? In the quest of saving a couple of cents in fuel? The only reason Start / Stop is there is to help manufacturers meet CAFE fuel economy standards. At leas tin the US. In the EU it's mandatory.
My biggest concern would be engine oil pressure. Sure the manufacturers might have beefed up the starters and voltage system to cope with 3 to 5 to 20x more starter cycles than cars without the "feature" but they surely haven't addressed the oiling issues, PCV pressure spikes (RMS on the M177?), or literally any of the other repercussions?
It's hilariously bad that auto start/stop takes action the second before I even hit the road, out of the neighborhood. My oil temp is still, what, 40°C when it activates? Effectively giving me double the cold start wear?
I'm very convinced about purchasing a Launch Creader Elite 2 as I see it has "variant coding"... which according to various sources may be used to disable eco start/stop or set it to last used position memory.
On my 2018 E300 4Matic (Sport) -- the auto Stop/Start feature is always on when you start the car. I simply turn it off. I get the environmental friendly factor, however, for me, common sense tells me that there is added use, wear and tear, etc., on the various parts that are involved. I know MB claims it's minimal, doesn't hurt, and so on. But common sense tells me different, LOL. I don't think there is a fuel savings. That said, I was told the feature has to be included to meet some standards or something. I don't know. However, if that's true, I think that if they didn't have to include it -- they might not! LOL.
Here's an updated version of the module I bought to permanently change my car's START-STOP default setting to off:
It's available on eBay: https://tinyurl.com/2ygry9kt
I was just about to bc change the battery and I noticed a sticker on it that says 4/22. The battery should not need replacing after only 3 years.
my car won’t go into stand by mode because of insufficient charge. My auxiliary battery arrives in a few days. I hope I can just replace that one and my problems will be gone
Last edited by Whatmypilot; Jul 30, 2025 at 12:03 AM.
I was just about to bc change the battery and I noticed a sticker on it that says 4/22. The battery should not need replacing after only 3 years.
Depending on the quality of the battery, 3 years is not out of the question. We're not driving 1972 Chevys...modern cars eat batteries. I tend to buy the top end battery I can find (but not the $500 batteries - last one I bought and installed myself was $250) and I only count on 4 years.
I’m only trying to fix it because of the construction they are doing. They closed lanes and I sit in traffic and my car just eats through its tank. MB told me it’s my auxiliary battery that manages the start stop eco. They quoted me for $420 just for the battery. I found the same thing on Amazon for like 50$.
You have one of two things that are going to get "eaten"...fuel....or the engine (starter, battery, pistons....) Any time I get into any of my three cars with that stupid "Eco" button it is disabled before I even get the seat belt on.
2019 E 450, 2016 E350 4matic (retired), 2018 Ford Edge Sport, 2008 Porsche Boxster
Originally Posted by MNIAW
Depending on the quality of the battery, 3 years is not out of the question. We're not driving 1972 Chevys...modern cars eat batteries. I tend to buy the top end battery I can find (but not the $500 batteries - last one I bought and installed myself was $250) and I only count on 4 years.
The original battery in my 2019 E450 is still going strong - so I count on a minimum, not maximum of 4 years.
A good way to check your battery is to go to "standby mode": When I do I usually get 22 to 28 weeks. After charging which I periodically do, I get 32 weeks.
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