W204 Strange Behaviour

[markwightman]

Ever since I bought my C200 it has displayed the following odd behaviour. Every so often:
- The temperature gauge drops to zero
- The engine fan comes on
- The heater comes on.
If I pull over and switch off the ignition and then switch on again everything returns to normal.
This used to happen typically if I was driving at higher speed, say on a motorway, and slowed down, e.g. came off the motorway. It also used to be relatively infrequent, like once every couple of months or so.
Now it is getting more frequent happening several times a week, and even multiple times in a day. It also happens shortly after starting, and isn't associated with the fast/slow thing anymore.
Also, on a few occasions recently, the yellow engine warning light has been coming on and staying on when the temperature gauge thing happens. If I leave it switched off for a few hours the warning light returns to normal.
I had the temp sensor replaced a couple of years ago but it made no difference.
Anyone got any ideas what could cause the combination of symptoms described above?
Many thanks.

 

[chills128]

Hi,

Did you ever get a solution to this problem. I have the exact same problem except for the heater coming on.

 

[markwightman]

Hi,

I never did. But the good news, for me at least, is that I still have the car and it has all but gone away. It hasn't happened in about a year, I reckon.

 

[mattkh]

Hi,

I never did. But the good news, for me at least, is that I still have the car and it has all but gone away. It hasn't happened in about a year, I reckon.

What electronic/electroical items have been changed during your ownership.

 

[chills128]

Hi,

I never did. But the good news, for me at least, is that I still have the car and it has all but gone away. It hasn't happened in about a year, I reckon.

Cool thank you for your response,

I haven't gotten a response on how to solve the problem. I usually stop, clear the error and continue driving.

I am thinking of taking it to a mechanic for service, maybe they will see something I don't. I've changed thermostat and temp sensor.

 

[markwightman]

I tried everything. Had it put on diagnostics, both at a main dealer and at an independent. Changed thermostat and temp sensor (twice). No change. The baffling thing was that I described the symptoms in detail to an MB technician and he wasn't even able to tell me what sequence of events might be occurring to give these symptoms, let alone what might be causing them. Good luck, and please post if you crack it. Might be useful for future reference!

 

[markwightman]

What electronic/electroical items have been changed during your ownership.

Need to have a think about this. Other than bulbs, nothing comes to mind. Will think more.