W211 Battery protection convenience features disabled

[Avantgarde nut]

I am trying to find out the cause of the above warning. The car starts and drives normal. If I drive really gently the warning doesn't come up. As soon as I put my foot down the warning comes up. I start work really early so I start it up put the lights on etc and it's fine. I would have thought that this would be the time the warning would come on. The battery in the boot is 12 months old I don't know about the auxiliary one. I am guessing either the auxiliary battery an alternator problem or the battery control module. I am just wondering what other people's experiences have been. Thanks in advance Martin


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[whitenemesis]

Get the car on STAR read any fault codes. It could be any of those you listed. It could simply be too many short journeys. Has the BCM been updated with the latest coding? If the Aux battery is original get it changed

 

[Alps]

as above, normally be the batteries due to short journeys, you have two in the w211

 

[amgant]

sounds like the same problem I had on my e55 it was the auxiliary battery

 

[E55BOF]

If it's the auxiliary battery, I can't see why the warning would not come up when the car is driven gently. Mine is getting tired, but the warning only comes up from time to time when I start the car, not while I'm driving.

 

[Avantgarde nut]

Today I have tested both batteries. The large in the boot shows 12.6v first thing this morning without it being run. The auxiliary battery showed the same. I started it up and the large battery read 13.8v and the auxiliary 13.6v. I disconnected both batteries and reconnected and made sure both where tight. As yet no warning but I'll know more tomorrow as I am on a 70 mile round trip. I'll keep you posted.


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[streethawk]

Has the face lift w211 have 2 batteries. ? I thought just pre facelift with sbc?

 

[4life211]

It is the aux battery that trigger that message.it shows good values but after a time it fail.replace it.

 

[Alex Richardson]

So what now? After disconnecting and reconnecting them, still the same warning?

 

[whitenemesis]

See post #2.....

 

[Dec]

Is the car alarm in working order?

If it’s the original system then its now 13 years old, the alarm siren can cause odd faults when it start to go bad.

Dec

 

[Avantgarde nut]

Update. Having disconnected the batteries cleaning the terminals and re tightening. On a 70 mile round trip the fault would appear to be cured. I would guess that the positive terminal on the battery in the boot wasn't as tight as it could have been. Thanks everyone for your input [emoji106]


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[whitenemesis]

Update us again in a few days....

 

[Peter103]

I posted a couple of days ago that my 'Auxiliary battery malfunction' had popped up, so been following this with interest, I've booked car in tomorrow pm to have it checked, though it hasn't come on today, bit awkward as am in Spain and main dealer is about as good with English as I am with Spanish, ie not very,
Though he did mention Star when I booked it last Friday. Will post verdict tomorrow, my car E 350 9g coupe.

 

[Peter103]

Took car in yesterday afternoon as arranged, though 'Aux Battery Malfunction ' hadn't appeared since Sun morning, they did their checks and said the boot battery needed replacing, which they did, after giving the new one a top up charge, which took about an hour, all done under warranty, in total we were there about an hour and half, No airs and graces, no cups of tea and biscuits, in Spanish dealers, but I must say they come across as very efficient, and instill a certain confidence in the customer, the showroom and reception area are seperated from the workshop by a long clear glass wall, and customers are able to watch their cars being worked on while waiting. So, a good result all round, We will be leaving Spain next Sunday and returning to merry England, hope the weather there improves by then.

 

[Avantgarde nut]

Still no warning. Appears to be solved


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