Coolant Warning appears
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Joined: Aug 2009
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
Coolant Warning appears
I was wondering if anyone has had the coolant warning flash up on the dash when the car does not need coolant. Sometimes it might appear for only a second or two, other times longer. It does not record a message in the system messages. Could it be a faulty sensor?
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From: 1 hours drive north of Sydney Australia
2007 W204 220CDI Classic Sedan
If it still alarms then take it off to the MB workshop .
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
I have not checked this on our 204 yet. On the 203 the same light comes up if your screen washer fluid is low - yes - crazy I know! Check your washer fluid 
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
Thanks Guys, Yes I will top up the washer tank as well, as it might be giving off the wrong message. I topped up the expansion tank a couple of days ago with just a tiny bit in case it was on the threshold, but message came up today again. Rang Mercedes Benz and car going to them, they seemed to think it is a faulty sensor, as they had heard of the problem before. I don't know what type of coolant it is in it as the car is fairly new. Its blue to green in colour.
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From: Orlando, FL
2026 AMG GT63 Pro
yeah i've been getting a coolant message on start-up pretty regularly now for the past month...i think it may have something to do with the cold?
nonetheless, something else to take care of...BOO
nonetheless, something else to take care of...BOO
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
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From: Richmond Hill, Ontario, Canada
MB 2008 C300 sport, 2008 Rally blue Subaru Impreza 2.5 SI 1995 MB C280 W202
I've a 2008 C300 the Canadian version. The check coolant light on in my dash board when i left the car overnight and it happen at least 3 times a week.
I bought my car in for dealer service B 40,000 KMs and they did a pressure and stress test on the coolant and the rest of the pipes to make sure there is no leak.
Nothing found. Talked to MB mechanic and off the record.... this been happening to all the C class and the workaround is to top up to the level and monitor it.
MB dealer want to charge me $ CAD 127 and talked to the Service Manager and he waive the charges but charge me the SERVICE B which is fair enough.
After the MB dealer top up the coolant, and so far so good (touch wood) and for the past 2 weeks,it been gooooooodddd.
Yeah, started like two months ago and comes on every now and then. Dealer said its not a big deal cause they checked it out and it was fine.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Sorry - no need for Google - just search the forum on things like this. Buy it from your dealer & dilute 50/50 with deionised water. They don't sell premix in the US. Canada - I don't know. Don't polute the system with other coolants - you have a chemical extender in your radiator tank & can cause gel formation in the cooling system. 325.1 & previous Benz coolants like 325.0 are compatible & miscible/fungible.
Last edited by Glyn M Ruck; Nov 3, 2009 at 06:16 AM.
Thread Starter
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
Just an update. Took the Car to Mercedes Benz dealer. They have not been able to identify why the warning comes up. Checked codes, software etc and cannot find anything wrong. Funny though, on the way home from picking the car up, the warning came up for about 5 seconds and then disappeared. The dealer is now looking further into it.
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From: 1 hours drive north of Sydney Australia
2007 W204 220CDI Classic Sedan
Just an update. Took the Car to Mercedes Benz dealer. They have not been able to identify why the warning comes up. Checked codes, software etc and cannot find anything wrong. Funny though, on the way home from picking the car up, the warning came up for about 5 seconds and then disappeared. The dealer is now looking further into it.
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
Just an update guys. Didn't have a lot of satisfaction form the dealer. No problems showed up on their computer. Matter is now being dealt with by MB Australia. They seem to think they might know what the problem is but will need to look at the car maybe in next week or so.
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W204 2008 C350
I also just got the coolant warning error msg upon starting the car early Saturday morning. I dismissed it by hitting 'OK' and continued to my destination, and eventually the warning disappeared. I have kept an eye out for the last couple of days but nothing so far. My car is a little over 1 yr old with about 14k miles on it, so even though it looks like it must have been a temporary glitch with the warning sensor itself, I wonder if its normal(possible) for coolant level to decrease in such a short period of time to trigger a valid warning message?
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08 MB
Another owner with the "low coolant" message. Like others the message went away quickly and hasn't come on again but it's only been one day.
Seems to be a common issue from reading this thread but if it's just an intermittent glitch the dealer would have a problem tracking it down so I wouldn't blame them. Not much one can do if all parts check out okay with standard diagnosing. This isn't like a nail in your tire and easy to identify.
Seems to be a common issue from reading this thread but if it's just an intermittent glitch the dealer would have a problem tracking it down so I wouldn't blame them. Not much one can do if all parts check out okay with standard diagnosing. This isn't like a nail in your tire and easy to identify.
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From: Orlando, FL
2026 AMG GT63 Pro
Just wanted to say that I took it to the dealer and they gave me some coolant to top off the tank with when the car is cold in the morning...
Since I topped off the tank, no more issues!
There were no problems with the system apparently - just seems that the sensor is ubber-sensitive and when the fluid contracts when cold out it trips it...
Since I topped off the tank, no more issues!
There were no problems with the system apparently - just seems that the sensor is ubber-sensitive and when the fluid contracts when cold out it trips it...
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
I just wanted to provide an update to my original post of a few months ago. After one dealership gave me the run around with my Coolant Warning message that kept coming on, I went to another dealership upon the advice of Mercedes Benz Australia. With the car being off the road for 3 days, they replaced some control unit or module and the message has now not appeared. Although I only picked the car up today and it has not been driven around much, I am hoping the problem has been fixed.
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From: Bandar Seri Begawan, Brunei
15 E200CGI SPORT
I just wanted to provide an update to my original post of a few months ago. After one dealership gave me the run around with my Coolant Warning message that kept coming on, I went to another dealership upon the advice of Mercedes Benz Australia. With the car being off the road for 3 days, they replaced some control unit or module and the message has now not appeared. Although I only picked the car up today and it has not been driven around much, I am hoping the problem has been fixed.
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From: Melbourne, Australia
2009 Mercedes Benz C350 CDi
I will be able to provide you with more details. They are sending me detailed paperwork on the work done. They just didn't have it all ready when I picked up my car. I will post more details about the part when I find out.
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From: Bandar Seri Begawan, Brunei
15 E200CGI SPORT
