How do I change the temperature fan sensor?

[Vx-Man-G]

Hi guys,

Think I need to change the sensor which kicks the radiator fan into action as the car is always shooting up to 3/4 high and I'm just thinking that the fan isn't coming on soon enough. With the recent oil cooler issue I'm thinking the sensor has gunk on it.

It's a W204 C200 CDi.

Where is this sensor located?
What does it look like?
How does it remove and replace?

Thanks.

 

[Vx-Man-G]

Anyone - please?

 

[LostKiwi]

Is it a separate sensor or is it under ECU control from the sensor the ECU uses?

 

[Vx-Man-G]

Is it a separate sensor or is it under ECU control from the sensor the ECU uses?

I have no idea?
I would assume its a sensor that screws into the radiator somewhere?

 

[LostKiwi]

A lot of modern cars don't use a separate sensor. Cheaper to do it in software.

 

[Vx-Man-G]

A lot of modern cars don't use a separate sensor. Cheaper to do it in software.

How would that be done in the Software?

Is there not a sensor which plugs in and tells the car to turn the fan on?

So basically, we're noticing that the temperature goes up to 110, im assuming the fan then kicks in as it stays at 100. It used to sit happily at 90 degrees.

My thinking is that as the oil cooler was goosed a couple of weeks ago, the sensor might need changing as its probably got some oily residure on it so not reading properly, or sending information properly.

 

[LostKiwi]

How is it done in software?
Easy. Temperature sensor passes temp to ECU, ECU decides it's getting too warm, tells fan to switch on. Same sensor is used to determine fuelling and anything else that needs accurate temperature measurement.
Simple.
Oil won't affect temperature readings as it is not a heat insulator. It's more likely that if oil got into the coolant system it's blocking the flow in the radiator or the thermostat is gummed up. If you think about 5his logically the temperature gauge is working normally so why would a second sensor (assuming there is one) not work correctly too?

 

[Vx-Man-G]

How is it done in software?
Easy. Temperature sensor passes temp to ECU, ECU decides it's getting too warm, tells fan to switch on. Same sensor is used to determine fuelling and anything else that needs accurate temperature measurement.
Simple.
Oil won't affect temperature readings as it is not a heat insulator. It's more likely that if oil got into the coolant system it's blocking the flow in the radiator or the thermostat is gummed up. If you think about 5his logically the temperature gauge is working normally so why would a second sensor (assuming there is one) not work correctly too?

Yeh good point, now you say that I am thinking it is the stat as we had oil in the coolant following failure of the oil cooler.

Is the thermostat an easy diy change?

Car is a 2010 W204 C200 CDI.

Thanks.

 

[LostKiwi]

No idea - never done one on a 200CDi.

 

[alexanderfoti]

Oil in coolant
overheating
headgasket?
Air in cooling system still?

One coolant temp sensor is used for the information. The fan is a variable duty PWM fan and does not "click" on and off so a temp gauge the shoots up and down is either a bad sensor (unusual) or is reporting the true value

 

[mioba]

In these conditions a fan is not needed to cool the engine to be honest.
You have another problem.

Did you check the coolant circuit for signs of oil and did you flush it using a proper cleaner if so. Checked the level is OK

I would be inclined to first the above. Then a sniffer test.

Then the stat. Any stat is easy to change.


Thinking its a sensor is going to cost alot of money. Thinking is expensive, correct diags and elimination is key.