Hi everyone.
I've been getting a low coolant msg on my dash, but only on startup in winter cold temps (I live in Toronto). There is no warnings when the car is warm, or when the car is started in warmer temps (spring, summer and fall).

I've read up on the dreaded headbolt issues on the M156, and I see that a low collant msg can be a warning sign. I thought there was a fix on 2012+ models...

I had this issue last winter as well. The SA (and AMG tech) said there was no problem and I didn't think anything of it.

I'm probably gonna stop by to see my SA next week, but do you guys think this is a serious problem? How often do we have to top up our coolant in normal conditions?

Thanks

I should also say that there have been no CEL's of any kind and no real noticeable change to the driveability. I can't notice any smells, but in all honesty I don't even know what coolant smells like (I admit that I love driving her, but don't have much technical knowledge of cars).

Any info/suggestions would help at this point.

Thanks

You have revised headbolts, so it's likely not that.

Check the level, could be a failed sensor (serviced a 2012 ML350 Bluetec that had this issue), or there could be a leak. Since you're under warranty still I'd let them deal with it.

Could just be due to the cold temps.

+1 agreed

Ask your mb dealer for your Engine number.

If your Engine number are higher than 060658 you should have no Head bolt issue

I have a '14 and I got one of these messages the other day. It was cold, and I had the car parked on an incline, and I think the combination set the sensor off. Had no messages since. It's super easy to check your fluid level - have you looked at the coolant in the reservoir? If not do it but not when the car's hot for God's sake. But at least check it.

Your coolant is a bit low
The level drops when cold
It rises 15 mm as temp goes from 68 f to 195 f
Refrence your manual
Adjust level when cold, there is a black/white tab in the middle of the tank
The level should be at the center of the tab
Do not overfill, probably a few oz, add a bit and check, repeat

I have studs and got this message the other month. The sensor is really sensitive.

You are correct
Very tight range on the sensor
Perhaps < 1"
So if marginal when warm outside it may trip when the level drops due to cold weather

OP
With car stationary for more than 8 hours
Open hood (it's a pull lever under dash left of the steering wheel)
Release hood safety latch
Open hood to 90 deg
Locate reservoir (from front left side blk/wht tank)
Put a rag on the cap and remove CCW
With a flashlight peer into the tank
On the backside you will see a tab in the middle height of the tank
It is blk & wht at the same level the black and wht tank halves are joined
The coolant should be right at the black/wht transition on the tab
Add the coolant mix until it is at the proper level a bit at a time checking every few ounces

This should take less time than it took me to type this
<5 minutes
Far less that taking it to the dealer lol
They may charge you since this maintenance not a failure
If level is correct and light is on then take it

Tough crowd!

I could have said open the 'front' trunk

I have experienced this as well - received the message a few times over the past couple of weeks but only when the car has been sitting overnight in temps below 32F. It immediately goes away when the car warms up...I'll check my levels tonight and add a little if needed. I assumed it was temp/sensor related due to the cold.

Same behavior here. I don`t think it's a big deal, I'll follow Ingenieur procedure, thanks!

Any coolant will do I assume? Or do I need to buy a particular one

Best to get the correct coolant from MB, mix it 50/50 and top off the coolant to the correct level. This will maintain the long service life of the factory coolant in the car. Should be the blue colored coolant.

Coolant chemistry has become very complicated. Also, color means nothing these days. You have a silica packet embedded in your cooling system that replenishes protective additives. Don't even think about using anything other than OE...there is no longer a one-size-fits-all solution to coolants.

Oh wow ok thanks for the info!

So what is spec'ed for our cars?
325.0
326.0
325.6
326.6
???


http://bevo.mercedes-benz.com/d/d/en/Spec_310_1.pdf

These look ok and are locally available
http://www.valvoline.com/pdf/Zerex_G...l_Bulletin.pdf

http://www.valvoline.com/pdf/zerex_g48.pdf

Looks like the g48 is bmw oem
I have some pre-mixed 50/50 with distilled water
I would not have concerns topping off with it

Well my dealer sold me 325.0 and it's the same color as my OE coolant fill.

IIRC our cars use the hybrid organic acid technology (HOAT) coolant. I know people who use Zerex G-05 which also is HOAT in their Mercs as it is so recommended by Valvoline.