W218 Eco mode still not working after new Aux battery

Page may contain affiliate links. Please see terms for details.

Junction10

New Member
Joined
Oct 6, 2023
Messages
4
Location
Walsall
Car
CLS 220D AMG Line
W218 2016 CLS 220D

My ECO mode stopped working earlier this year. I just get the yellow ECO text on the dashboard and not the green box with inverted text, so that tells me it’s not activated…
I also noticed the air conditioning wasn’t pushing through chilled air when on its coldest setting, plus even when set at 20 degrees for example and when the ambient temp is between 18-22, I’d hear what sounds like air blowing across the top of a bottle coming from behind the vents..

My dealer checked the air con and said there’s nothing wrong with it - and that it doesn’t blow chilled air - it only ever gets (at most) 10 degrees BELOW the ambient temp.. which is strange because it USED to blow chilled air that would numb your fingers when I first had it, and so does my wife’s Nissan Juke..

Anyway, they said it’s the auxiliary battery.. I thought it might be a sensor in the heating matrix - which might be causing the ECO mode to not meet all the right parameters to be enabled (especially if it thinks it hasn’t met the correct ambient temp), but they were positive it’s the auxiliary battery.

So today, they fit a new auxiliary battery, which cost me £200 - parts and labour.

I don’t know what they’ve actually done because the ECO mode still doesn’t work and the text is still yellow, not green.

Drove home (30 minute journey) and start/stop didn’t engage once.

Thought maybe I need to give it a bit of a run-in (though should you, really, if it’s a brand new battery??) so gave it a blast down a dual carriageway… still yellow and disabled.

Not happy at having spent £200 for nothing… even more unhappy that they said it was fixed but clearly just turning on the ignition shows it isn’t…

Any ideas please?

J
 
Well it is possible it is something else but this is marginal at best.
I would have put the new battery on charge before fitting, but failing that it could take a few days before it is charged up enough to work the stop/start - there are a few other parameters before it works as well.
Personally, I would leave it for up to a week before considering doing anything else.
Let us know how it goes 👍🏻👍🏻👍🏻
 
Well it is possible it is something else but this is marginal at best.
I would have put the new battery on charge before fitting, but failing that it could take a few days before it is charged up enough to work the stop/start - there are a few other parameters before it works as well.
Personally, I would leave it for up to a week before considering doing anything else.
Let us know how it goes 👍🏻👍🏻👍🏻
Just been for a 20 mile blast along the motorway with aircon off, screen off, usb cables unplugged etc.. hoping that might give the new battery a kick.
Eco still in yellow on the dash.. I’ll give it a few days to see what happens.

Its just bizarre that i go to pick it up and they say its all done and working, when clearly its not.

J
 
  • Like
Reactions: Ted
Check the voltage on both the new Aux battery and the main battery before starting the car.
You should have a reading of 12.6v+ for a fully charged lead acid battery, more if you have an AGM battery which I suspect you have.

68151.jpg
 
  • Like
Reactions: Ted
Check the voltage on both the new Aux battery and the main battery before starting the car.
You should have a reading of 12.6v+ for a fully charged lead acid battery, more if you have an AGM battery which I suspect you have.

View attachment 147889

Ok - so now I’m confused, and bitter…

I’ve brought it back to the dealer. They’ve had a look and now telling me it’s the main battery, which is only producing 11.6 volts… and they expected me to pay £370+ for a new battery and labour.

I’ve argued because they charged me for an auxiliary battery and said that fixed it but it hadn’t.. and the engine data on the vehicle diagnostics screen in the car says the battery is producing 14.7v so I don’t know what’s going on.

We’ve agreed that I’ll just pay for the new battery and they’ll waive the labour charge.. but still not happy at paying £200 last week for a fix I didn’t actually need…

We’ll see if it finally fixes the eco mode!
 
Might be sensible to buy a CTEK Battery Conditioner, either the MX5 or MX7. Certainly cheaper than new battery, as using the CTEK on your car will make the battery last longer too.
Many on this forum use CTEK.
 
Could be the auxiliary battery was knackered as well. 14.7 v is the output from the alternator charging the battery. It tells you nothing about the battery. The battery voltage is measured without the engine running.
Does sound like the main battery has a problem and probably needs changing. Is it the original? If so, its done ok.
 
A battery can have one single cell failure which could lead to a correctly read charging voltage when the engine is running but falls back below the "Fully Charged" threshold level once the engine is stopped. If the "Fully Charged" status flag is not set, the ECO-drive will not activate. The thing is that this kind of cell failure can still make the car crank without problems and there will be no alternator warnings in the dash board or any DTC's set.

A complete diagnostic test should include a load test (hundreds of A's for a short period simulating a crank) as well as the battery voltage when the engine is running and all consumers (Infotainment, heated seats, head-lamps on, AC/Fan running, etc.) at a specific engine RPM. This to rule out any problems with the alternator.
 
  • Like
Reactions: Ted
Similar thing on my Range Rover, new battery, still no stop start. Dealer said "drive it more". Took it to an Auto Electrician who had it for a couple of days as he would try something then let it go to sleep, then same again. Found a parasitic drain. Fixed, no problems after that. Also as stated above, get a Ctek, all my cars have one.
 
I had the same problem, fitted a brand new main battery for £139 from Tayna and worked straight away.
 
Stop starts works perfect on my 2013 204, i think it's on original batteries and i always turn off the stop/start.
 
Just replaced my main battery for the same reason…..£161 delivered …. Bosch. 12.3v on my old battery.
 
If you have a trickle charger, maybe trickle charge the battery overnight, read the voltage the next morning and see if that works
 
Ok - so now I’m confused, and bitter…

I’ve brought it back to the dealer. They’ve had a look and now telling me it’s the main battery, which is only producing 11.6 volts… and they expected me to pay £370+ for a new battery and labour.

I’ve argued because they charged me for an auxiliary battery and said that fixed it but it hadn’t.. and the engine data on the vehicle diagnostics screen in the car says the battery is producing 14.7v so I don’t know what’s going on.

We’ve agreed that I’ll just pay for the new battery and they’ll waive the labour charge.. but still not happy at paying £200 last week for a fix I didn’t actually need…

We’ll see if it finally fixes the eco mode!
Any update on the matter!! Is the issue fixed?
 

Users who are viewing this thread

Back
Top Bottom