Coolant Sensor C250 W204 2010 location

[Paul Calman]

Hi, My coolant fan starts to run as soon as I start the engine, first slow then in 20 or so seconds ramps up to full speed. I have looked on-line and it says that the sensor is at the rear of the head behind the cam sensor however it's not on mine! The VIN number is WDD2042032F5855993 and the engine number is 65191130380590 if this helps. If anyone could help I would be very grateful. Thank Paul

 

[AMGeed]

The sensor plugs into the thermostat which is Item #80 in the diagram below.
The sensor is Item #90

M 651.911 - COOLING-WATER CIRCULATION > Mercedes EPC Online > nemigaparts.com

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[Paul Calman]

The sensor plugs into the thermostat which is Item #80 in the diagram below.
The sensor is Item #90

M 651.911 - COOLING-WATER CIRCULATION > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. Engine - Power Systems COOLING-WATER CIRCULATION.

nemigaparts.com

Many thanks for your reply. I thought that sensor was the one for the temp gauge in the car?

 

[Paul Calman]

The sensor plugs into the thermostat which is Item #80 in the diagram below.
The sensor is Item #90

M 651.911 - COOLING-WATER CIRCULATION > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. Engine - Power Systems COOLING-WATER CIRCULATION.

nemigaparts.com

 

[Paul Calman]

Thank you BTW my VIN was incorrect, should have read WDD2042032F585993

 

[Paul Calman]

Hi,

The sensor plugs into the thermostat which is Item #80 in the diagram below.
The sensor is Item #90

M 651.911 - COOLING-WATER CIRCULATION > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. Engine - Power Systems COOLING-WATER CIRCULATION.

nemigaparts.com

Many thanks for your help. I have received the new part and connected it to the cable and have the same problem. I also noted that because I did not install the sensor the temp gauge in the car did not show any temp ( as I would expect). When I looked at the diagram you sent me the sensor #90 is shown to connect to #100?? The #80 is shown at the top of thermostat not the bottom. Please could you take a look and let me know. Look forward to hearing from you. Many thanks.

 

[AMGeed]

^ Hi Paul,
What you are saying re #90 connecting to #100 and #80 at the top of the thermostat is what I see too.
But, #80 is not the position, its just referring to the thermostat. #80 could have been printed under the thermostat.

I assume you bought Part#90, the sensor and have connected it to the cable #901 and pushed it into the temperature sender unit #100?

 

[Uncle Benz]

The cooling fan will run at high speed for a number of reasons including canbus communication faults. You can’t assume it’s a temperature sensor fault without a read of the fault codes I’m afraid. A decent diagnostic session is your best bet.

 

[Paul Calman]

^ Hi Paul,
What you are saying re #90 connecting to #100 and #80 at the top of the thermostat is what I see too.
But, #80 is not the position, its just referring to the thermostat. #80 could have been printed under the thermostat.

I assume you bought Part#90, the sensor and have connected it to the cable #901 and pushed it into the temperature sender unit #100?

Hi,
Yes the new sensor #90 was plugged into #901 cable and pushed into sender unit #100. The location is as per the diagram (lower part of the stat), however there is another sensor on the thermostat which is located on the top of the housing (shown in the diagram to the left of the number #80) which also has two wires connecting to it. Could this sensor be related to the fan? I'm guessing that the problem may be something else completely. I took the car to a garage and all they did was reset the errors and charged me £72. Thanks for your input.

 

[Paul Calman]

The cooling fan will run at high speed for a number of reasons including canbus communication faults. You can’t assume it’s a temperature sensor fault without a read of the fault codes I’m afraid. A decent diagnostic session is your best bet.

Hi, yes I beginning to think that it may well be something else. The thermostat housing has two sensors, one located near the bottom (the one I've replaced) and also another sensor located at the top of the housing - I thought I would try the obvious things first. If you have any thoughts I would be grateful. Ultimately I know that a full scan should be done. (I did buy a cheep-o OBDII scanner but it did not show any faults - junk ha ha. Thanks

 

[AMGeed]

^ A Mercedes specialist (not main dealer) should be able to diagnose the problem quite quickly.

Where are you located so maybe someone can recommend a specialist nearby?

 

[Paul Calman]

^ A Mercedes specialist (not main dealer) should be able to diagnose the problem quite quickly.

Where are you located so maybe someone can recommend a specialist nearby?

Thanks for your reply. I'm in Combe Martin, North Devon, about 10 miles from Barnstaple

 

[AMGeed]

Mmm closest independent Mercedes specialist I know of is a fair distance away in Clevedon Avon.

Mercedes Specialist Bristol - Repairs for your Mercedes Benz

Experience top-notch Mercedes-Benz servicing, repairs, and wheel alignment in Bristol. Trust our skilled technicians with 70 years of combined expertise.

avantgarde-automotive.co.uk

Hopefully someone closer to you can recommend somewhere suitable.

 

[Paul Calman]

Mmm closest independent Mercedes specialist I know of is a fair distance away in Clevedon Avon.

Mercedes Specialist Bristol - Repairs for your Mercedes Benz

Experience top-notch Mercedes-Benz servicing, repairs, and wheel alignment in Bristol. Trust our skilled technicians with 70 years of combined expertise.

avantgarde-automotive.co.uk

Hopefully someone closer to you can recommend somewhere suitable.

Thanks for your info anyway. I guess I'll have to reply on a local outfit to take a look. Cheers

 

[mioba]

Soooooo many posts every day - what could it be or thinking they can be an old school mechanic.
Yes you an be an old schol mechanic on purely mechanical parts bit for the reat forget it.

I think i will just paste - get the codes read.

It is just parts darts, money burning and a waste of time otherwise.

I like fixing bits on my cars. Best thing i ever got was the icarsoft. Its paid for itself every use.

A bit of a rant but with some advice!