Hi,
I am in Rangiora, I tried replying by private messages but you are set up to not receive any so I could not reply that way.
I think you have two unrelated separate problems with the lights, You can either replace the switch and then get the auto light repaired or have the auto light looked at first.
On my C200 I leave the switch in the "A" auto position this fixes the flickery intermittent park lights which happens when the switch is in the”O” off position and saves buying a new switch.

Yes I think a visit to a dealer is required to either run a diagnostic or calibration of your new light sensor, I think ring first and get a quote for these operation would be best first step.

I buy my Mercedes parts from Pelican parts in the USA, I use this web page to find p/n.
https://www.ilcats.ru/mercedes/?VinA...41&language=en

Regards
Dave.

Hi NZ-Merc , Im an Aucklander, just been reading one of your posts about the headlight switch in a C300 (W204). I have an issue with mine where every now and again I see one of the the park lights has been left on. (Even though in switch position "0")
After switching between "0" and the park positions on the switch a couple of times it goes out. Sounds like it could be the switch ? do you know is there a local supplier or just the main dealer ?
As well as that Im getting the auto light malfunction error in the dashboard , when I turn the lights on any of the positions clockwise from "0" just give me full headlights regardless of the ambient light.
I have today replaced the Light / Rain sensor behind the rear view mirror with no improvement, do you think these 2 issues could be related ? Is there any calibration required on the sensor I replaced.
Hope you can help,,,,