Intermittent 'Check Coolant' warning
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From: Toronto, NYC
2002 Mercedes Benz C230 Coupe
Intermittent 'Check Coolant' warning
Over the last couple of days, my car seems to be throwing an intermittent 'Check Coolant' warning. Happens randomly only during some starts.
There is no wind shield washer fluid warning accompanying it, so it cant be the faulty sensor. I even topped off the wind shield fluid just to make sure, and I still see the warning.
I know my car MY and engine is known for the 'coolant leaking into transmission' issue. Im concerned that this is now acting up. Ive owned the car for 2.5 years now and never had any issue. So should I be worried and check for this coolant leaking into transmission issue now? If my car was going to have this issue, wouldnt it have happened sooner?
On the flip side, it could just be a dip in coolant level, although I have no idea where the coolant couldve gone. I have no leaks or puddles.
Any suggestions?
Thanks guys.
There is no wind shield washer fluid warning accompanying it, so it cant be the faulty sensor. I even topped off the wind shield fluid just to make sure, and I still see the warning.
I know my car MY and engine is known for the 'coolant leaking into transmission' issue. Im concerned that this is now acting up. Ive owned the car for 2.5 years now and never had any issue. So should I be worried and check for this coolant leaking into transmission issue now? If my car was going to have this issue, wouldnt it have happened sooner?
On the flip side, it could just be a dip in coolant level, although I have no idea where the coolant couldve gone. I have no leaks or puddles.
Any suggestions?
Thanks guys.
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From: Orange County
2005 C Wagon (No snickering please!)
I am confused. What does washer fluid have to do with coolant level?
My experience with German coolant sensors whether from Ford, Porsche (real Porsche's don't have coolant), BMW, Audi, or Opel is that they get sticky. Most cars have a float with a magnet and a reed switch in the coolant tank.
Suck out the coolant covering the float/sensor in the tank. remove the sensor and clean it well with warm soapy water. Rinse well with alcohol, dry and replace. If it was just gummy, you'll be fine. I would replace the fluid with genuine product mixed with distilled water if anywhere near 150K miles. A shop with an exchange system would be better than a simple drain and refill. If the thermostat is visible and easy to change, I'd do that too. It also allows a peek inside the engine, if you are curious.
My experience with German coolant sensors whether from Ford, Porsche (real Porsche's don't have coolant), BMW, Audi, or Opel is that they get sticky. Most cars have a float with a magnet and a reed switch in the coolant tank.
Suck out the coolant covering the float/sensor in the tank. remove the sensor and clean it well with warm soapy water. Rinse well with alcohol, dry and replace. If it was just gummy, you'll be fine. I would replace the fluid with genuine product mixed with distilled water if anywhere near 150K miles. A shop with an exchange system would be better than a simple drain and refill. If the thermostat is visible and easy to change, I'd do that too. It also allows a peek inside the engine, if you are curious.
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Joined: Jun 2008
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
On older cars low washer fluid triggers a low coolant warning - crazy but true.
These cars do loose some coolant over time due to evapouration of the water fraction etc. even though it's a closed system.
You may need one of these.
These cars do loose some coolant over time due to evapouration of the water fraction etc. even though it's a closed system.
You may need one of these.
Last edited by Glyn M Ruck; Nov 5, 2011 at 10:26 AM.
Thread Starter
MBWorld Fanatic!
Joined: May 2009
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From: Toronto, NYC
2002 Mercedes Benz C230 Coupe
I am confused. What does washer fluid have to do with coolant level?
My experience with German coolant sensors whether from Ford, Porsche (real Porsche's don't have coolant), BMW, Audi, or Opel is that they get sticky. Most cars have a float with a magnet and a reed switch in the coolant tank.
Suck out the coolant covering the float/sensor in the tank. remove the sensor and clean it well with warm soapy water. Rinse well with alcohol, dry and replace. If it was just gummy, you'll be fine. I would replace the fluid with genuine product mixed with distilled water if anywhere near 150K miles. A shop with an exchange system would be better than a simple drain and refill. If the thermostat is visible and easy to change, I'd do that too. It also allows a peek inside the engine, if you are curious.
My experience with German coolant sensors whether from Ford, Porsche (real Porsche's don't have coolant), BMW, Audi, or Opel is that they get sticky. Most cars have a float with a magnet and a reed switch in the coolant tank.
Suck out the coolant covering the float/sensor in the tank. remove the sensor and clean it well with warm soapy water. Rinse well with alcohol, dry and replace. If it was just gummy, you'll be fine. I would replace the fluid with genuine product mixed with distilled water if anywhere near 150K miles. A shop with an exchange system would be better than a simple drain and refill. If the thermostat is visible and easy to change, I'd do that too. It also allows a peek inside the engine, if you are curious.
I guess replacing/topping up the coolant seems to be the logical first step. I had no idea that coolant could be lost from the system other than through spills/leaks etc. Weirdly the last few days seem to have been error free. Not sure whats going on. Maybe it throws the error only on cold starts...ill examine next time.
Glyn, that picture..is that the coolant thermostat?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Listen to Russell but I can assure you that on early cars the Windshield washer level circuit also sets off the coolant level warning. You will find many theads to that effect here. So the problem could be either the coolant level sensor or windscreen washer sensor as well.
Last edited by Glyn M Ruck; Nov 12, 2011 at 10:27 AM.
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From: Toronto, NYC
2002 Mercedes Benz C230 Coupe
Thanks guys.
Not sure how a cooling fan problem would throw a coolant level error though :S
Glyn, Im aware of the windshield washer sensor issue...but its not that throwing the code this time. Haven't seen a windshield washer warning, and I topped it off just to make sure and I still get the error.
Ive been in Australia for work over the past couple of weeks, so havent had a chance to take a look at this problem. I will now that Im back. Im hoping that a simple coolant top-off will fix it.
Not sure how a cooling fan problem would throw a coolant level error though :S
Glyn, Im aware of the windshield washer sensor issue...but its not that throwing the code this time. Haven't seen a windshield washer warning, and I topped it off just to make sure and I still get the error.
Ive been in Australia for work over the past couple of weeks, so havent had a chance to take a look at this problem. I will now that Im back. Im hoping that a simple coolant top-off will fix it.
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From: Toronto, NYC
2002 Mercedes Benz C230 Coupe
Hmm...thats weird!
This has happened to me a few times now...when my windshield washer was low, I end up getting both warnings at the same time. Usually the low coolant warning shows up by itself first, and within a few hours, I get the windshield washer fluid warning as well.
I did some research and read somewhere that both sensors are wired in series in the same electrical loop. So when the first one (windshield washer) is tripped, it throws off the resistance limits for the entire circuit thereby triggering both warnings. Not sure about the validity of that theory though.
This has happened to me a few times now...when my windshield washer was low, I end up getting both warnings at the same time. Usually the low coolant warning shows up by itself first, and within a few hours, I get the windshield washer fluid warning as well.
I did some research and read somewhere that both sensors are wired in series in the same electrical loop. So when the first one (windshield washer) is tripped, it throws off the resistance limits for the entire circuit thereby triggering both warnings. Not sure about the validity of that theory though.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
They had changed it by the time my car was built but many 2000, 2001, 2002 cars throw a low coolant message for both conditions. Your car might be after that.
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From: Toronto, Ontario, Canada, eh!
2003 C230 Sports Coupe, Paprika Metallic Red, Auto, Pano, Leather
Basically, since the coolant reservoir is at the front of the car and the sensor is there too,.... when the nose of the car is pointed upwards, there`s a bit less coolant in the reservoir and thus it`s more likely to trigger the sensor and thus the warning.
Well,... that seems to have been my issue and since I`ve topped off the coolant,.... no more coolant warning and limp mode.
