C250D 2018 auto start/stop not working

[DebL]

Hi New to Mercedes. My husband just bought a 2018 C250D AMG with eco start/stop. But is isn't working. The light by the (if there was a) gear stick is green, the light on the dash is amber. Suggestions? I have been told many factors need to be in place before it will work, I am not sure what they all are but are they that impossible the get them all to match so it works? If not, a bit of a con. I have a wee VW and the start stop works with heated seats, heated windows, fans etc..... Any help greatly appreciated.

 

[Blobcat]

Hello and welcome,

Probably the most common issue for eco-mental stop start not working is a poor battery. The lack of use due to 'Rona has caused a lot of cars to have battery issues.
In your case with a "new to you" car I'd want the vendor to be putting a new battery on for you - Assuming it wasn't a private sale

If you can get a a digital mulitmeter and measure the battery voltage - it should be ~12.6v with the engine and everything else off (key out of ignition) and ~14.4v with the engine running

 

[alexanderfoti]

Most likely the battery, but a few other things can cause it. It's possible to check 100% on Mercedes diagnostic equipment.

 

[Gazwould]

Leave it as it is .

Many Mercs have had this issue .

It'll cost money to fix and is bad for the car prematurely wrecking chain tensioners , starter motors , batteries , alternators and engine mounts .

 

[DebL]

Hello and welcome,

Probably the most common issue for eco-mental stop start not working is a poor battery. The lack of use due to 'Rona has caused a lot of cars to have battery issues.
In your case with a "new to you" car I'd want the vendor to be putting a new battery on for you - Assuming it wasn't a private sale

If you can get a a digital mulitmeter and measure the battery voltage - it should be ~12.6v with the engine and everything else off (key out of ignition) and ~14.4v with the engine running

thanks for the detail, I have passed to my husband!

 

[Srdl]

Welcome Deb. The battery should be fine on a 2018 car and probably justs needs a good run to get it fully charged or a spell with a battery conditioner connected. Often, cars for sale sit around doing nothing for weeks or months and the recent cold weather won’t have helped either.

 

[onefortheroad]

I put my battery conditioner onto the main battery under the bonnet for a good few hours last weekend and its going green after 4 miles of driving . Not that I use it tbh . I turn it off by the key if I'm gonna be waiting ages in a queue of traffic.

Someone will mention the 7.5amp fuse in the boot to disable it completely. Very soon.

 

[Gazwould]

Only works on older Merc that first got the abomination contraption so definitely W204 not W205.

 

[Jim2]

I put my battery conditioner onto the main battery under the bonnet for a good few hours last weekend and its going green after 4 miles of driving . Not that I use it tbh . I turn it off by the key if I'm gonna be waiting ages in a queue of traffic.

Someone will mention the 7.5amp fuse in the boot to disable it completely. Very soon.

I'm not a fan of stop/start either, but I just manually switch it off on the console. Standard operating procedure at this stage. Get in seat. Put on seat belt, start engine, switch off stop/start. 2nd nature by now..

 

[Gazwould]

Except for the day you forget .

Like a stick in the spokes of a wheel...

 

[Jim2]

Except for the day you forget .

Like a stick in the spokes of a wheel...

Yeah..and then you get the reminder pretty quick ☺

 

[DebL]

ok so lets just pretend we wanted the check the auxiliary battery - where is it? We can't see it :-(

 

[alexanderfoti]

The aux battery on these is a capacitor bank, stored in the passenger footwell, underneath the carpet. They do not behave like a battery and give a warning on the dash when failed usually.