Overheati

[BigNath89]

Hi, I own a w205 estate and on cold start up in the mornings the temp gauge is reading 90 degrees. This morning when I started the car it was in the red and telling me to turn off the engine. I don’t think the car can be overheating on start up. Does anyone know what the problem may be? Thanks in advance

 

[AMGeed]

Welcome to the forum
It sounds like you have a faulty coolant temperature sensor.
The Part is around £20.
If you have a Mercedes specialist, he can diagnose the problem for certain. I'm just making an educated guess

 

[BigNath89]

Thanks for that. I’ve just been under the bonnet and found the sensor unplugged. Just recently had springs, discs and pads done. There’s a pipe running behind the sensor coming from the brake fluid so guessing the mechanic knocked it off. Now not sure if this would have caused any damage to the car

 

[AndrewOl]

It is unlikely there has been any harm done. When you plug it back in does the temperature indicator read normally?

 

[BigNath89]

Thanks for that. I’ve just been under the bonnet and found the sensor unplugged. Just recently had springs, discs and pads done. There’s a pipe running behind the sensor coming from the brake fluid so guessing the mechanic knocked it off. Now not sure if this would have caused any damage to the car

I don’t think the sensor I found unplugged is the temp sensor, you wouldn’t happen to know where that is? Thanks

It is unlikely there has been any harm done. When you plug it back in does the temperature indicator read normally?

The sensor I found unplugged isn’t for the coolant temp. Think it was for the rear screen heater as that wasn’t working and now is and the temp is still reading high. I’m not sure where to find the temp sensor as I was going to do it myself if it’s easy access. Thanks for replying

 

[AndrewOl]

Not familiar with the OM651 but according to this it is on pipe between the thermostat and the water pump. I'm sure someone with more knowledge of the engine will be able to help a bit more.

https://mymotorlist.com/wp-content/uploads/2021/08/ruk-om651.pdf

 

[BigNath89]

Not familiar with the OM651 but according to this it is on pipe between the thermostat and the water pump. I'm sure someone with more knowledge of the engine will be able to help a bit more.

https://mymotorlist.com/wp-content/uploads/2021/08/ruk-om651.pdf

Thanks mate. That helped me find the sensor. Really easy to get to right at the front of the engine