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Robert, UK Qualified Car Technician
Category: Mercedes
Satisfied Customers: 4708
Experience:  Fully qualified / self employed garage technician in the UK
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Hi, I bought an s class 320 l diesel recently. I have noticed

Customer Question

I bought an s class 320 l diesel recently. I have noticed a coolant warning light appearing when I arrive home which is on a steep hill. The coolent warning light only appears when I am going up the hill.
Can you help?
Submitted: 4 years ago.
Category: Mercedes
Expert:  Robert replied 4 years ago.



Hopefully i can help..


One of the first checks to make would be the actual coolant level in your coolant reservior tank and see if its a little low - make sure you check this when the engine is cold and top if required...The fact you say the light only comes on going up hill could mean as and when the nose of the car points up hill the coolant maybe/or will become higher at one end of the tank than the other until the car levels out of course and could be the level sensor maybe picking this up or be it at the end the level is lower and think the level has dropped suddenly - until as suggested above the car levels out and the level is even again in the tank as above i would check the level first to top if required and then see how that long as the car inst actually over heating then it does sound like this is whats maybe happening..I do hope this helps

Customer: replied 4 years ago.


I did check the level and the coolant level seems ok?

Any other advice?

kind regards,



Expert:  Robert replied 4 years ago.

Hi..there.. thanks for getting back..


Ok..if the coolant level is fine and there are no other obvious issues as far as you can tell..then the next check really would be the level sensor itself could be playing up or bad connection maybe..but like I say above if the coolant light goes out when the cars on level ground or going down hill even then it could be as simple as what I mentioned before and may not be an issue in as above the next stage would be the check or have checked the level sensor..