I too have noticed this. It can be almost at the 90 mark and then the next time I check it’s closer to the 60 mark.

 

What mileage is yours mate? Can’t be right can it. Should sit at the same temp once it’s warmed up?

 

Guys, this is not normal and usually points to a thermostat failing. I would get it back to the dealer to investigate asap as it can cause damage to other engine parts.

 

That’s what I’m thinking, doesn’t seem right to me. Booked in at Merc on Friday so will see what they say. Surely thermostat wouldn’t go at that low mileage though?

 

It sounds like a working temperature control system to me. People have got used to cars showing a fake constant 90, as my VAG vehicle frustratingly does. The gauges are now coded so that one the actual temp reaches ~70 to 110 the gauge will display 90, outside of this the gauge will display the actual recorded temp.

They dumbed the display down because they determined people didn't need to see actual outputs - thus I couldn't see the warning signs that my water pump was failing. I miss old cars and their no nonsense outputs.

 

That doesn’t make sense for mine though as it goes up and down between 70 and 90, should stay at a constant 90 then like every other car I’ve owned surely?

 

Well, that assumes that Merc have programmed this car to be a dumb gauge. What you describe is a gauge reading actual temps.

With regards other car's you've owned, VAG made this change in the mid 90s. Stuff before that actually told you what was really going on. If you've only owned more recent vehicles then there's a chance you've never read a gauge that's showing actual temps

 

I get ya. Will ask Merc tomorrow when it goes in, cheers for the help. Just come from a leon cupra to this so everything is a bit different !

 

I've messaged the lass and asked her to periodically have a look at the readout and see if it's a 'dumb gauge' or actual readings, if she see's it before she heads home I'll tell you what our A200d does

 

Thanks for that mate, appreciate it, be helpful to have something to compare it to.

 

I have an A200 AMG Line, I'll keep an eye on my temps for you too.

 

That would be great, thank you

 

I disagree with the poster regarding fluctuating temps being the norm. The water temp should get to around 90c and remain there. Any variation to this is indicative of a fault. I know through experience of this happening on several of my past cars. On some it was the thermostat failing and on one car it was the coolant temperature sensor.

 

thanks for the info, I really don’t know myself but car going into Merc today for them to look so hopefully will get sorted! thanks again , very helpful forum this one ??

 

I have a 5 month old A200 AMG line premium, done 2k miles, my guage definitely fluctuates. 3 previous VW's didn't

 

Even once it’s up to normal operating temp Ian? That’s what mine is like, as soon as you drive on a faster a-road for instance the temp drops down! Baffling but don’t know if it’s normal or not !
cheers

 

Update.
Possible thermostat issue but Mercedes want it for a few days to test.
Only trouble is the next available courtesy car isn’t for about a month!
The guy said the needle shouldn’t really fluctuate once up to temp.
Cheers for all the replies.
Will update further when hopefully they fit a new stat!

 

The lass has reported back. She’s said that the needle does fluctuate a little bit but mostly is in the middle. Her drive is quite constant just sat on the motorway.
I’ll be driving it tomorrow I think so I’ll have a look

 

Nice one cheers, would be interested to hear what yours does. Hopefully mine is the thermostat going and will put my ever guessing mind at rest!

 

Drove it at the weekend, must admit I was hung over and forgot to look most of the journey! But after some relatively relaxed A / B roads leading to the M40 the gauge was in the 3rd of the 4 sectors. After being sat on the M40 for 10 minutes at a 'rock and roll' 65mph the gauge went to dead centre and remained there.

 

Cheers for that, it’s kind of confirmed what I was already thinking that mine ain’t right. Hopefully thermostat should sort it then. Is yours a petrol or diesel by the way? (Not that it should make a difference tho I suppose)
Cheers

 

It's the 200d, it will make a difference, TDI engines run quite a bit cooler than in-direct and petrol. Plus the bigger lump will have a more stable temp i.e. less fluctuation.

Yours still sounds almost normal to me. a fluctuation of 15. So sat in traffic it gets a bit warmer, perhaps the stat has opened but with no airflow it's not made much of an impact. Then you start driving again and the airflow quickly drops the temp and thus the stat closes and your temp rising back to 90 again.
Perhaps the stat is opening a little early, but I'd be surprised.

I'm very interested to hear the outcome - if they do change the stat I'd ask for the old one back so you can stick it in a pan at home and see what it's doing

 

It's the 200d, it will make a difference, TDI engines run quite a bit cooler than in-direct and petrol. Plus the bigger lump will have a more stable temp i.e. less fluctuation.

Yours still sounds almost normal to me. a fluctuation of 15. So sat in traffic it gets a bit warmer, perhaps the stat has opened but with no airflow it's not made much of an impact. Then you start driving again and the airflow quickly drops the temp and thus the stat closes and your temp rising back to 90 again.
Perhaps the stat is opening a little early, but I'd be surprised.

I'm very interested to hear the outcome - if they do change the stat I'd ask for the old one back so you can stick it in a pan at home and see what it's doing

Will update when it goes back into Merc (end March now though unfortunately).
I understand what your saying but it still doesn’t seem right to me, all journeys now once warmed up you can watch the gauge going up and down like a yo-yo between 70 & 90. No good for my OCD lol.

 

yer, that doesn't sound right, should be more stable than that. Shouldn't be yo-yo'ing like that on every journey

 

Hello guys, i have the same issue, with W177 A180 benzine. I am waiting Mercedes to call me to go the car to the service. The mechanic on the telephone, was brink us the car.

 

Mine goes to be looked at in a couple of weeks time so will let you know what they say.
Likewise, let me know how you get on with yours please!

 

So i went yesterday to the service! They plugged the car to the ECU, they checked the thermostat of the car and it was ok! They did upgrades to MBUX, and machine! After the first ride, i noticed the temperature not changing to much! And i didn't have the big changes from 92 to 72 degrees, some 4-5 degrees changes.

I told them why Mercedes not calling us for ECU upgrades, and they told me that the car is going to take the upgrades only if something is wrong in the car.

So i had a problem, an ECU upgraded was already out, and i didn't knew the existence of it!

Congratulations to Mercedes

 

So i went yesterday to the service! They plugged the car to the ECU, they checked the thermostat of the car and it was ok! They did upgrades to MBUX, and machine! After the first ride, i noticed the temperature not changing to much! And i didn't have the big changes from 92 to 72 degrees, some 4-5 degrees changes.

I told them why Mercedes not calling us for ECU upgrades, and they told me that the car is going to take the upgrades only if something is wrong in the car.

So i had a problem, an ECU upgraded was already out, and i didn't knew the existence of it!

Congratulations to Mercedes

hmm, interesting. Mines actually going in for software updates as well next week before they check the thermostat so I’m hoping it could just be that now! will keep my fingers crossed.
Thanks for the letting me know ??

 

I am going to raise an issue to Mercedes, i hope others will come with me, in order to receive notifications when new upgrades for ECUs are rolling out! Why to have a problem and and ECU update that i didn't knew the existence fixed my car!

This is bad customer support!

 

I am going to raise an issue to Mercedes, i hope others will come with me, in order to receive notifications when new upgrades for ECUs are rolling out! Why to have a problem and and ECU update that i didn't knew the existence fixed my car!

This is bad customer support!

I totally agree. Mine only recently went for a main dealer service so you would think the updates would of been done then!
You would think in this day and age there would be a system in place to keep customers informed so they have the choice wether to update or not.

 

They told me, that if you do not report something as an error they not upgrade the ECU, that is wrong for me! Because the ECU updates fixes error of bugs that are in the software!

 

Unfortunately still the same issue! Nothing changed from the ECU upgrade!

 

Oh no, that’s not good!
Was hoping that had sorted it for you. Back to the dealer. Is it no better at all then?

 

Some models have an aerodynamic shutter.
Data card code 5U3 Airpanel (Radiator with adaptive closing function).
More likely to be controlled by software than the thermostat .

 

Some models have an aerodynamic shutter.
Data card code 5U3 Airpanel (Radiator with adaptive closing function).
More likely to be controlled by software than the thermostat .

I’m still hoping software updates will solve mine, going in on Friday so fingers crossed. Thanks for the info

 

My software update removed from drivers screen MBUX the destination map! I am very angry!

 

I've read of a few update issues across several forums now.
Hardly surprising the dealers don't want to get too involved in firmware updates when it sometimes breaks the car.
Moving to Linux as definitely caused them some headaches in MBUX too.
No doubt a lot of retraining being required across the techs and developers.

 

The technology is new, they don't realize the change! It's very sad!

 

did you ever get this sorted on your car? Mine has been cancelled twice due to the covid19 outbreak so hasn’t actually been into be looked at yet!
Just curious?
Thanks

 

Had my a180 premium since November and my gauge has done this from new just thought it was normal with this car.

 

maybe it is meant to do it then if yours is a brand new one?does yours go up and down between 70 & 90 constantly even after the engine is warmed up?
Thanks