well my valeo alternator is at 172k and works just fine so yes they do make some good things

 

Time to bump this old thread. Anyways, I got too tied up with other things and forgot about this. The weather got warmer, and now this problem has completely disappeared. Fingers crossed that it won't magically reappear in the winter. Thanks for all those who replied. Will give an update if this problem shows up again.

I'm still scratching my head and wondering if and how it would be possible for a VR to fail *only* when it's cold? Unless there's a hairline crack somewhere in the circuitry..

 

Ok, I had exactly the same error - mornings when cold and occasionally at random times - "Light sensor failure - drive to workshop". Read the forums... Took my 2004 C180K SE to the local garage and had the battery "load" tested. Battery was in fine shape. During lunch yesterday took a knife and spoon handle to the control panel located by the rear view mirror in the ceiling, popped the covers off, re-seated (un-plugged and re-plugged) all the connectors that plug into the mini computer thats located in that area... YIPEEE FIXED!! Happy days!!

Howard :-)

 

Hi I am Annette from South Africa. I have the same problem, workshop says nothing is wrong. The car battles to start and the light sensor warning sends me to workshop. How did YOU solve the problem? Thank you.

 

Hey,
I just bought a mercedes C200 coupe from 2001, im not so sure it was a great purchase. I have had 2 MB earlier versons from around 1990 and they worked great. All this new electrical stuff scares me =)

It has The "Licht sensor, visit workshop" message.
I live in Sweden and this car is imported after about one year from Germany at the beginning of 2003, thats ofc. why it says Licht and not light I presume.

My question, does my Mb have a light sensor for switcing on/off the lights, i dont think so but i really dont know to be honest, its my wife who drives the car so I havent really examined it.

I find very little about this problem on the internet, Mercedes in Sweden support basically suck unless I spent alot of money on this old car which i dont wanna of course , can someone help me on the way here?
i have no problems with the car, no starting problems or no lights going nutz or similar as a few other people in this thread.

Best regards
/Per

 

I haven't seen a w203 that didn't have auto headlights. Look at the switch it should have an auto setting. So yes it should have a light sensor but make sure your electrical system is good because that seems to be a common cause.

 

Had this issue with the "light sensor" visit workshop show up on my display years ago. Had my battery load tested and turned my battery was not 100% causing the "light sensor" warning. Would show up on the display once in a while, usually after the car was not used for 10-12 hours or more. Once the battery was replaced this warning never appeared again. That was about 8 years ago.

 

Yes, the error is cause by low system voltage. This can be from either a poor battery or a failed voltage regulator. For me it was the VR that needed replacing, but for some, a new battery did the trick. Interestingly enough I have not heard of a failed light sensor actually causing the problem. The car just thinks the sensor has failed when there isn't enough voltage.

 

I have a similar problem. The lights from de right ( passenger side are flashing) and before that the license plate right side ( driver side) it started flashing until it even burned the inside support of it. Do someone think the VR or the alternator would be the problem?
During the day I'll have a look at the voltage and see the limits it's running.

 

After a test of a few km the voltage raised from 11.7V to 14.4V. I think is fine. So where could be the problem?

 

This error came up when i started experiencing low Voltage on my battery. I tried charging the battery and realized i needed to replace it.
I replaced by battery and and the error never came up again.

 

Just had this issue after my battery died (the hatch did close completely during some extremely cold conditions). I checked with my iCarsoft MB2 scanner and saw some history codes all relating to voltage. So all signs point to a weakened battery. Those big group 49 batteries are pricey but swapping the battery fixed every single low-voltage issue and cleared that light sensor error.