Mercedes w205 C350e plug in hybrid 2017 - coolant temperature jumping up and down

[wildsnake]

Hello

I have a Mercedes w205 C350e plug in hybrid 2017 and I have a problem with coolant temperature which is jumping up and down
If I drive low rpm ...no problem, but if I accelerate hard and brake the temp is going very fast up to 120 and in 3-5 seconds goes back to 90....same situation when I drive up to 120-140 km/h!
I've changed the electric water pump and no change!
what could be?

 

[gianton]

Most likely a new thermostat is needed.

 

[sonic]

Hello

I have a Mercedes w205 C350e plug in hybrid 2017 and I have a problem with coolant temperature which is jumping up and down
If I drive low rpm ...no problem, but if I accelerate hard and brake the temp is going very fast up to 120 and in 3-5 seconds goes back to 90....same situation when I drive up to 120-140 km/h!
I've changed the electric water pump and no change!
what could be?

Going up to 120 in 3-5 seconds, I would be looking at the temperature sensor. Does the engine smell very hot?

 

[wildsnake]

Going up to 120 in 3-5 seconds, I would be looking at the temperature sensor. Does the engine smell very hot?

Nope...not at all...ventilator is starting...but coolant is not very hot
I have changed the sensor located in cylinder head!