Coolant level low message
Thread Starter
MBWorld Fanatic!
Joined: Feb 2003
Posts: 1,414
Likes: 339
From: Charlotte, NC
Had: 1987 300TD, Had: 2004 C230 Sport Sedan, Have: 2014 E350 Sport, Have: 2019 S450
Coolant level low message
I'm presently about 800 miles away from the wife, and her '14 E350 (M276 NA) has been giving intermittent warning messages for Coolant Level Low for the last 2 days.
On her way to/from work, the message will appear and then clear itself a couple of times, with the A/C not functioning when the message is displayed.
The Boss isn't very car-savvy, but she was able to get a jug of the correct coolant. She opened the reservoir, and found that the reservoir still had fluid in it, but she wasn't sure about how much.
She added coolant until the clear bottom section of the reservoir was full (level up to black plastic top section), but the message continues to intermittently come and go.
Questions:
- Has anyone else encountered this issue? If yes, how was it resolved.
- If it were your wife, would you tell her to keep driving it for a week until you could deal with it? Or would you tell her to park it until your return?
Thanks in advance for any information provided.
On her way to/from work, the message will appear and then clear itself a couple of times, with the A/C not functioning when the message is displayed.
The Boss isn't very car-savvy, but she was able to get a jug of the correct coolant. She opened the reservoir, and found that the reservoir still had fluid in it, but she wasn't sure about how much.
She added coolant until the clear bottom section of the reservoir was full (level up to black plastic top section), but the message continues to intermittently come and go.
Questions:
- Has anyone else encountered this issue? If yes, how was it resolved.
- If it were your wife, would you tell her to keep driving it for a week until you could deal with it? Or would you tell her to park it until your return?
Thanks in advance for any information provided.
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
Likes: 6,547
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Tell her to get distilled water of say 1 US gallon or some equivalent liters.
Even better if pre-mixed MB certified coolant matching existing coolant in the car, which maybe blue one which is no more in production, but new one pink
can not be mixed with old blue. Total proper flushing must be done to use pink from blue coolant.
Hence distilled water is easier.......if only a week.
The coolant reservoir bottle is approx 750cc capacity , the white see thru region ( as full mark ).
ONLY IF FOR 1 WEEK before you get home.
Everday before engine start, tell wifey to check coolant level and do proper fill up.
Don't let her fill up while engine is hot when low coolant alarm trigerred, it will be unsafe for here, albeit MB coolant reservoir is a smart design
with emergency venting going downward when you undo the cap for a few turn, before one can actually remove the coolant cap.
However, id daily loss is equal to 300cc or almost 1/2 of reservoir, stop using the car....too risky.
Even better if pre-mixed MB certified coolant matching existing coolant in the car, which maybe blue one which is no more in production, but new one pink
can not be mixed with old blue. Total proper flushing must be done to use pink from blue coolant.
Hence distilled water is easier.......if only a week.
The coolant reservoir bottle is approx 750cc capacity , the white see thru region ( as full mark ).
ONLY IF FOR 1 WEEK before you get home.
Everday before engine start, tell wifey to check coolant level and do proper fill up.
Don't let her fill up while engine is hot when low coolant alarm trigerred, it will be unsafe for here, albeit MB coolant reservoir is a smart design
with emergency venting going downward when you undo the cap for a few turn, before one can actually remove the coolant cap.
However, id daily loss is equal to 300cc or almost 1/2 of reservoir, stop using the car....too risky.
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
STAY OR DRIVE
Wife E350 is truly low on MB coolant.
She refilled using proper pre-mix chemistry coolant, that is either YLW or BLU (not green) - but dash light still comes on.
I think engine is low and the level she adjusted skillfully went back inside the engine.
Refill tank again the same way to half mark (not max to the top!) until level stays at the half mark.
> TOP OFF PROCEDURE...
Best way to refill is start with a COLD ENGINE only (not HOT engine with scalding pressure)
- Open tank top off to the half-mark
- start and attend running engine idle for 15mn
- top off tank as system is lowering level (less than 1Gal.)
- reseal tank cap do not open afterwards while hot.
- shut engine off
> STOP OR GO...
The decision is based on what size leak is active.
It's hopefully only the slow leak around VALEO radiator seams... these M276-NA engines always leak even new.
A large leak won't hold hot coolant pressure.
Hopefully she dont warp her engine heads.
She refilled using proper pre-mix chemistry coolant, that is either YLW or BLU (not green) - but dash light still comes on.
I think engine is low and the level she adjusted skillfully went back inside the engine.
Refill tank again the same way to half mark (not max to the top!) until level stays at the half mark.
> TOP OFF PROCEDURE...
Best way to refill is start with a COLD ENGINE only (not HOT engine with scalding pressure)
- Open tank top off to the half-mark
- start and attend running engine idle for 15mn
- top off tank as system is lowering level (less than 1Gal.)
- reseal tank cap do not open afterwards while hot.
- shut engine off
> STOP OR GO...
The decision is based on what size leak is active.
It's hopefully only the slow leak around VALEO radiator seams... these M276-NA engines always leak even new.
A large leak won't hold hot coolant pressure.
Hopefully she dont warp her engine heads.
Last edited by CaliBenzDriver; Jun 28, 2025 at 02:58 PM.
Thread Starter
MBWorld Fanatic!
Joined: Feb 2003
Posts: 1,414
Likes: 339
From: Charlotte, NC
Had: 1987 300TD, Had: 2004 C230 Sport Sedan, Have: 2014 E350 Sport, Have: 2019 S450
Thanks for the replies.
Proper coolant was blue. Level did not drop after she added to top of clear section. Message was displayed even after filling to that point.
I can’t find any info as to where the MAX level actually is, but I think at the clear/black joint she should be just above max.
Can anyone remember where the MAX level is on that reservoir?
Proper coolant was blue. Level did not drop after she added to top of clear section. Message was displayed even after filling to that point.
I can’t find any info as to where the MAX level actually is, but I think at the clear/black joint she should be just above max.
Can anyone remember where the MAX level is on that reservoir?
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
Likes: 6,547
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Thanks for the replies.
Proper coolant was blue. Level did not drop after she added to top of clear section. Message was displayed even after filling to that point.
I can’t find any info as to where the MAX level actually is, but I think at the clear/black joint she should be just above max.
Can anyone remember where the MAX level is on that reservoir?
Proper coolant was blue. Level did not drop after she added to top of clear section. Message was displayed even after filling to that point.
I can’t find any info as to where the MAX level actually is, but I think at the clear/black joint she should be just above max.
Can anyone remember where the MAX level is on that reservoir?
Yes, clear plastic meet black plastic of reservoir is FULL mark.
If message is displayed even when reservoir is full, it could be loose connector at bottom of reservoir for coolant level sensor, or wire got cut.
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
BACK TO NORMAL
Give dash-light some time to go off to normal and coolant to go down into engine.
The key is to not drive a dry engine.
The cooling system on the M276-NA engine can accumulate extreme heat that boils off cooolant.
Sadly the pressure relief cap on the expension tank doesn't prevent that. As a result coolant leaks develops to relief pressure.
The only way to fix that is to disable stock heat accumulation - Then heat stays at a managed level.
The key is to not drive a dry engine.
The cooling system on the M276-NA engine can accumulate extreme heat that boils off cooolant.
Sadly the pressure relief cap on the expension tank doesn't prevent that. As a result coolant leaks develops to relief pressure.
The only way to fix that is to disable stock heat accumulation - Then heat stays at a managed level.
Last edited by CaliBenzDriver; Jun 28, 2025 at 03:49 PM.
Senior Member
Joined: Mar 2022
Posts: 267
Likes: 61
From: Chicago
Bi-Turbo E550 Coupe (W207)
Any M276 or M278 engine is notorious for coolant leaks. Even after you put more coolant in there's a leak likely in your system. Common points of leak: Plastic turbo to engine custom MB coolant lines (become brittle and crack due to age and heat), radiator, hoses to the radiator, expansion tank (including the cap needing replacement), etc. I recommend taking to a mechanic to assess all the common failure points. Also they should check to see if the gaskets that keep coolant separated from oil/fuel are fully intact. If any milky residue in the coolant expansion tank or in the fuel means they are mixing and that's end of the engine typically.
Also if it was my wife, yes I would tell her to keep driving it, and just top of the coolant and keep me informed if the warning message re-appears. I would expect it to re-appear but as long as she has coolant to continue to refill, for one week its manageable that she doesn't have to stop driving the vehicle. The big thing would be to only top off the coolant once the engine has cooled down and never try to put coolant in when engine is hot, teh cap for the coolant will likely be under pressure and it will be hot/steam would appear if you would open the coolant expansion tank when engine is still warm or hot.
Also if it was my wife, yes I would tell her to keep driving it, and just top of the coolant and keep me informed if the warning message re-appears. I would expect it to re-appear but as long as she has coolant to continue to refill, for one week its manageable that she doesn't have to stop driving the vehicle. The big thing would be to only top off the coolant once the engine has cooled down and never try to put coolant in when engine is hot, teh cap for the coolant will likely be under pressure and it will be hot/steam would appear if you would open the coolant expansion tank when engine is still warm or hot.
Last edited by ibbij; Jun 30, 2025 at 10:57 AM. Reason: Clarification
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Thread Starter
MBWorld Fanatic!
Joined: Feb 2003
Posts: 1,414
Likes: 339
From: Charlotte, NC
Had: 1987 300TD, Had: 2004 C230 Sport Sedan, Have: 2014 E350 Sport, Have: 2019 S450
Update:
My son was able to connect with a Launch Creader and found no codes for coolant level, but found 3 codes for cooling fan:
P048568 The power supply of the electric fan has a malfunction. There is incomplete information.
P069100 The output of electric fan 1 has a short circuit to ground
P048309 The electric fan has a malfunction.There is a component fault.
Codes were cleared, and returned immediately.
Has anyone seen a failure of the cooling fan give a 'Coolant Level Low' message?
They seem close, but not the same.
My son was able to connect with a Launch Creader and found no codes for coolant level, but found 3 codes for cooling fan:
P048568 The power supply of the electric fan has a malfunction. There is incomplete information.
P069100 The output of electric fan 1 has a short circuit to ground
P048309 The electric fan has a malfunction.There is a component fault.
Codes were cleared, and returned immediately.
Has anyone seen a failure of the cooling fan give a 'Coolant Level Low' message?
They seem close, but not the same.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Update:
My son was able to connect with a Launch Creader and found no codes for coolant level, but found 3 codes for cooling fan:
P048568 The power supply of the electric fan has a malfunction. There is incomplete information.
P069100 The output of electric fan 1 has a short circuit to ground
P048309 The electric fan has a malfunction.There is a component fault.
Codes were cleared, and returned immediately.
Has anyone seen a failure of the cooling fan give a 'Coolant Level Low' message?
They seem close, but not the same.
My son was able to connect with a Launch Creader and found no codes for coolant level, but found 3 codes for cooling fan:
P048568 The power supply of the electric fan has a malfunction. There is incomplete information.
P069100 The output of electric fan 1 has a short circuit to ground
P048309 The electric fan has a malfunction.There is a component fault.
Codes were cleared, and returned immediately.
Has anyone seen a failure of the cooling fan give a 'Coolant Level Low' message?
They seem close, but not the same.
Ise the scanner to run fan test. They dont usually fail electrically but mechanicaly from bearings.
This sounds like fan is not getting +12volts.
