Hi,all i seem to be having a problem with my atego,she is a 1223 on an x plate,seem to be having codes on the dash which not even our local merc agent can sort out well they are crap full stop.the problems are,
The fuel gauge dosnt work, new sender replaced, still not working.
When brakes are aplied the main beam head lights dim.
The exhaust brake warning light dosnt light up on dash.
The codes are as follow INS 0 0508 AND INS 0 3620.
I was hoping that someone might have had this problem before to shade some light on this many thanks and a happy new year to you all.
Sounds like a bad earth.
Happy new year mate but sorry i can’t help. 
Ben9:
Sounds like a bad earth.
It’s the GLOBAL WARMING 
torch it, claim on teh insurance an buy a decent motor. its an atego.
sorry i cant help but all atego’s i have driven have been seriously underpowered and a very uncomfortable ride. i dont like them
sounds like wiring problems and they a nightmare too fix unless you use the lee g method and torch it, i also wouldnt pay the bill for the parts that have been fitted and havent cured the faults, if the garage is as bad as you say then it maybe time to write a nice letter to the mercedes hq in englandshire and let them know how you feel about there dealership and the service you get
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I’d be looking for chaffing on the loom maybe at the back of the steering colum?
Certainly sounds like a wring fault. Certainly a problem with brake light wiring and main beam wiring. Start at the brake pedal and work up under dash, I would say.
Wiring faults are a lot of work and hassle to find, basically stripping the guts out the motor because it could be anywhere down the line. Ive heard there is a scanner machine that runs down the wire loom, kinda like a x-ray and it can pick up the faults easier than the naked eye. Maybe the machine im talking about is a mechanics ■■■■■■■■■ but I’m sure i heard about it 
We have the same problems with ours 0508 is the fuel gauage, change the gauage its self or either change the dash at £600 + VAT and get it reprogrammed, as the gauage is accurate if the dash isnt reprogrammed ie you have 160 litre tank and the dash thinks you have 200 litre tank. Check if theres a bulb in the exhaust brake light on the dash ours was the same, no bulb light. We never had the light dimming problems.