mookiebomber

I've been having the following problem for the past 4 days or so. My temperature gauge is going up and down, and the following icon flashes on my dashboard;

The temperature rages from the middle, all the way to sometimes above 100 degrees in a matter of seconds, it just jumps up and down.

I took the car to the shop, and they ran the scanner but they found nothing, claim everything is normal when clearly it isn't.

Here's some video of the issue, never mind the low fuel warning, just look at the temperature needle gauge and the icon that is there.

Strange thing is that it sometimes goes away on its own and the car goes back to normal.

LouZ

Possibly an air pocket and you are getting coolant surges.

steven1888

Well i think you have two message on the dash, one which is the low fuel which is nothing but i think the second message is the coolant message. Did you check if you need to add some more coolant into the car???

mookiebomber

Thanks for the reply. I did and even at the shop with my mechanic. Everything looked and felt normal, all the levels, and even the scanner was normal. Even today it showed again, but the strange thing is that after 5 or 10 minutes of driving, temperature goes down to normal and the dashboard warning is gone. Strange indeed.

Big Daddy

The gauge is moving too quickly to be a true reading
Could be a thermocouple failure

mookiebomber

That's exactly what I think. Either the engine is too hot or it isn't. In my opinion it can't be too hot for five seconds then a little less hot for another 5.

MDMercedesGuy

Mine will move that fast before the engine comes up to operating temperature. If you sit at a light or such it will creep up, but on acceleration it plummets. It also will do the same if you turn the climate control on on a cold day - the sudden surge of cold coolant and inclusion of the heater core in the loop knocks the temp down quickly.

That said, my gauge sits a bit higher than what is in the video at normal operating temperature.

mookiebomber

Any other opinions here? I have taken it to yet another shop this week, the mechanic claims there's nothing wrong with the car, that it doesn't heat up, yet I still get the problem. It still goes away after a few minutes and the car runs normal.

settesoli

Was there a solution????, my car does the same, the first minutes it's jumping up and down, blinking on and off.
It drives me crazy.

thanks in advance.................

tiyyara

I agree with others,
thermocouple (probe that measures temp) or sticky thermostat

hondafan

It's moving too quickly to be the thermostat. I'd say it's the temperature sensor inside the thermostat. I just recently did my thermostat. The temperature fluctuates much more slowly with a sticky thermostat.

The thermostat fails in an open position, so it's either flowing or not, and in winter months, that means the car would have a difficult time getting and staying up at operating temperature. The check engine light will also eventually come on for the thermostat failing because the car reads a temperature that's not quite normal operating temp (which is a preset value).


You can order just the temperature sensor without getting the thermostat, but if you order a thermostat, it comes with the sensor too. I wouldn't do the thermostat based on this though.

Riviera

Same opinion, can't be a mechanical/thermostat problem with a so fast moving needle, it's an electrical problem with the temp probe or a connector, so, first remove/put back connector on the temp probe, if it doesn't help, change the probe.

Pascal

settesoli

many thanks, will go to garage this week and try all this above.

will catch up later on..............

settesoli

6 months ago i replaced the temprature control module inside the car because it was in farenheit and i'm used to celcius, so i bought one on internet.

Now 6 months later strange engine temprature readings and engine temprature failures.

i put the old one in now and u can gues it, just did a test drive and it was fine, pffffff, hope it stays that way else i will delete post.

So i've learned now, only replace parts that belong to your chassis number, it saves u a lot of frustration.

thanks to the knowlage of one of the last good car mechanics, he said all tempature thingies are connected, even that inside the car, that set me thinking.

Glyn M Ruck

Electronic 4 Way thermostat.

https://mbworld.org/forums/5939612-post25.html

If you run too cold the car will throw a P0128.

acr2001

Another vote for a bad temp sensor here. It's obviously moving MUCH more than it would under any normal circumstances. Those changes in the temp gauge have absolutely nothing to do with running the heater or coming to a stop - they're far too quick and wide for that.

Someone else mentioned air pockets which is also a possibility, but I'm 99% sure this is an electronic issue. The readings are erroneous. It's got to be the sensor or wire, or ECU.

Glyn, do you really think it could be that variable with a bad thermostat?

Glyn M Ruck

acr ~ I don't think it is a bad thermostat. I just wanted to point out that a greater temperature fluctuation is now normal with the electronic 3 disc stat. The gauge should be well damped and not jump around. There could well be an issue with the cluster or temp sensor.

settesoli

What i recall it was p1999 electronic engine airsuction

mercedes4ever

Temp sensor.

settesoli

Problem didn't solved, go to other garage who will listen to me.

temp sensor is located at?

Kejdi2000

I have also the same problem. even on mercedes in Albania they cant explain it. strange (((

elborom

I think its the fan module .. Have the same thing and i replaced it now its steady as a rock

robertboone2

How did you know it was the fan control module versus the temp sensor?

I have a 2008 C350, with the following symptoms:
coolant warning, temp needle going up and down, a/c blowing but no cold area.

dpcravensC300

Ac issue/ needle jumps / coolant message... How much was your fan module ?

Kai_C63

I have the same issue. Already someone that can verify what the problem is? And how about that fan module, where is it located? in the fan assembly? (I have the 600W in my W204 part. A2049066802 and pictures of that fan don't show any module like the big silver module that is on the 400W version)