Hi All,
I am a first time Mercedes owner having just bought a 2002 C Class CDI Estate. The day after I got the car home I noticed that the engine was barely cranking and I only just got the car fired up. When I did I noticed that I too got the light sensor malfunction. I drove for about 25 miles, stopped, engine cranked over fine, no more messages. Ahhh I thought, the battery is on its way out and promptly ordered a new one and got it fitted (big aint they?!). Since then (a couple of days) I've had no such problem...
The question is... is is the light sensor that is draining the batteries or the light sensor complaining about the lack of battery power from old batteries?

 

WilkoUK, you bring up the same question I was thinking after reading this old thread.
A year ago I had the same fault code concerning the light sensor on my 02 C230 coupe (with an original battery). The car was getting harder and harder to start and eventually the battery died after the car sat buried in snow for two months. Even a battery charger would only get me going once but not a second time if I tried to restart the car.
After installing a new battery the light sensor fault disappeared and has never reappeared. In the electrical hierachy in the car perhaps the sensor is low man and does indeed serve as an indicator that a battery is due to fail. However, other people on this thread seem to have genuine sensor problems.

 

Its the battery. The sensor is voltage sensitive. A 6+ year old battery is done, period. Dont be an idiot like me, replace the battery first.

 

New update to old problem. Had a new battery installed 13 months ago. Worked beautifully for all of that time.
However, a week ago the car was stone dead. Not one indication of life. A boost got it going for one day then the same thing happened again and then a further repeat two days later.
Don't have electric seats so ruled out that problem. "Light sensor" issue always occurs just before battery dies. Most of the time it is a red herring.
Took car to dealer for diagnosis. The alternator had a faulty connection so it would start the car, charge the dead battery and then the battery would discharge back into the alternator due to an internal burned out diode.
Along with a new alternator I got a new battery (under warranty) since auto batteries don't like being drained to absolute zero three times in a row.
So far all is well.

 

Hi there, I got the "Undervoltage Consumer Defective!" message, too
(although I may be low in energy, as some friends claim, I don't feel defective! lol)

Could you folks kindly let me know:
can I replace the battery by going to a parts store like Pep Boys or Napa, etc?
Or, do I need to get a specific battery only from MB?
(I was thinking of one of those sealed no maintenance batteries to avoid corrosion and gasses,
and me not having to mess with distilled water, etc.)

Thanks!!!

 

Mercedes Roadside Assistance comes with EVERY Mercedes vehicle, no matter how old.

It is 24/7. 365 Days

They provide for free :

1) Jump start
2) Install new battery (free labor, you buy the OEM battery that they carry on the truck, so you get the full MB warranty on the battery, and a record of replacement on file at the dealer)
3) Install your spare tire (remove flat install spare)
4) Deliver a couple gallons of gas or diesel to get you to the nearest gas station.

Everything above is on Mercedes Benz's tab.

Roadside is available to do more services as well, such as lockouts, minor repairs etc, but they do require a fee.

As for lockouts, if your vehicle has an option for tele-aid, it becomes totallyworth it if you are stuck someplace with your keys locked in, to be able to have the MB satellite unlock your car for you!

Each dealer has a Roadside Tech with around a 30 mile radius of the shop.

Roadside Assistance doesn't cover towing.

Towing while under warranty is at the manufacturers discretion.

Otherwise, roadside will gladly arrange a tow for you, so you don't have to fuss with it.

The benefits of using MB roadside are great. We know about the vehicles. We have the special tools. You can stay warm and dry while somebody rescues your stranded vehicle.

1-800-FOR-MERCEDES

 

OK, Thanks, but this is a used c230k I bought, last year, at just under 100k.
Does that mean I still get the roadside assistance???!
It would be awesome if I could do it that way.

 

Those 4 points are free of charge for a lifetime for any MB ever built, doesn't metter how old, how many miles, how many owners car changed and you don't even have to be owner of the car.

 

can you send me a diagram on the light sensor access?

 

I recently took my C 230 sport 2015 to mechanic to repair the faulty sun/moon roof. after that, the massage 'light sensor visit workshop' start coming on everyday. Any
help is greatly appriciated. thanks.