richardkaiser78
Mercedes SL Coolant Level Warning
Summary of the thread
A 2010 Mercedes SL is showing a coolant level warning and a check engine light, indicating a coolant issue. Despite checking for leaks, none are visible. The problem could be due to a defective cable or plug connection, as confirmed by a workshop diagnosis, rather than a head gasket issue. The solution involved replacing the faulty connection and topping off the coolant.
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4 comment(s)
richardkaiser78 (community.author)
That's interesting about the radiator cap. How did you diagnose that? Were there specific signs, or was it just elimination? Did you also have a check engine light with the low coolant?
neleblaze8
Yes, the check engine light was on. I suspected a coolant leak initially, but saw nothing. The workshop pressure tested the system, and the radiator cap failed. Replacing it fixed the problem. I suggest a workshop pressure test.
richardkaiser78 (community.author)
Thanks! I took it to the workshop. It was a defective cable or plug connection, like the error code said. They replaced it and topped off the coolant. The repair cost 95€. Thanks for helping narrow it down!
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MERCEDES
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SL
neleblaze8
I also drive a Mercedes SL and had a similar issue. Is the radiator cap sealing correctly? A faulty cap won't maintain system pressure and can cause coolant loss through evaporation, explaining the low level without a visible leak.