Engine coolant too low

[A250mercy]

Hi,

Had an orange engine light come on some weeks ago, took it to local garage for diagnostic and was told the coolant temp is too low, but it’s not something he had seen before and cleared the fault code, and told me to take it back if it came on over the next few days.

Some weeks have passed and the light has come on again, but I have kept a more than normal eye on the coolant gauge in the dash, and this is almost always bang on in the middle of the gauge, and I don’t really want to be taking it back to the garage to be told the same thing for another fee.

anyone got any advice on what it may be? I would assume it may be the coolant temp sensor, but surely this wouldn’t be the case if the in dash gauge is reading ok?

 

[Trickythemerc]

I would not have thought low coolant temperature would cause the EML to come on.

 

[Smiley]

If it is the engine management light that has come on then you will need to get the car onto the MB diagnostics - known as "star". This can either be at the main dealer or at a mercedes specialist who has the same diagnostics capability as the main dealer. If you tell us whereabouts you are then someone may be able to recommend a specialist for you.

 

[kianok]

sounds like it’s the coolant that needs topping up and nothing to do with temperature.

 

[DSM10000]

sounds like it’s the coolant that needs topping up and nothing to do with temperature.

Why?

The OP's thread title may suggest this but he has been to a garage twice with no mention of coolant level being low or any being topped up.

The fault code was for low coolant temperature.

 

[DSM10000]

I would not have thought low coolant temperature would cause the EML to come on.

It can.

The ECU expects to see coolant temperature reach a certain figure based on external temperature and engine run time

This information is used to control fuelling during cold starts. If the temperature is lower than that expected then a fault code can be triggered.

 

[kianok]

Why?

The OP's thread title may suggest this but he has been to a garage twice with no mention of coolant level being low or any being topped up.

The fault code was for low coolant temperature.

Because I had the same message a few weeks after a water pump replacement.

The op hasn’t posted the fault code

He also states that the temperature gauge is reading correctly.

 

[DSM10000]

Because I had the same message a few weeks after a water pump replacement.

The op hasn’t posted the fault code

He also states that the temperature gauge is reading correctly.

He also visited a garage on two occasions and at neither time was it mentioned that the coolant level was low.

If it was then a "check coolant" message would be displayed and not a EML.

 

[markjay]

If your car is equipped with the M270 engine, then it's a common fault. The thermostat fails on these cars.

Unfortunately replacing it isn't straightforward. The thermostat comes complete with the housing and built-in electronics (and a heater). And, it's located under the engine so not easily accessible.

Take the car to a Mercedes specialist for a quote. My guess is £300-400 parts and labour.

Again, this is in relation to the M270 (and M274) engine, if that's what you have.

 

[kianok]

He also visited a garage on two occasions and at neither time was it mentioned that the coolant level was low.

If it was then a "check coolant" message would be displayed and not a EML.

Not true.

Coolant low does trigger the EML. and coolant low message.

 

[markjay]

I would not have thought low coolant temperature would cause the EML to come on.

It does on the M270/M274 engine. I had EML and this error message, and a new thermostat (fitted by Terry at WG) sorted it.

 

[markjay]

He also visited a garage on two occasions and at neither time was it mentioned that the coolant level was low.

If it was then a "check coolant" message would be displayed and not a EML.

The subject line of this thread appears to have the word 'temperature' accidentally omitted. I too thought intinitully it was referring to the coolant level.

 

[DSM10000]

The subject line of this thread appears to have the word 'temperature' accidentally omitted. I too thought intinitully it was referring to the coolant level.

Yes. I mentioned this in my first reply but al of the OP's posts mention low temperature.

 

[DSM10000]

Not true.

Coolant low does trigger the EML. and coolant low message.

I doubt it triggers the EML.
Why have two warnings for the same event?

On the rare occasion I have had a low coolant message (C320 with a failing expansion cap) there was no EML.

 

[kianok]

I doubt it triggers the EML.
Why have two warnings for the same event?

On the rare occasion I have had a low coolant message (C320 with a failing expansion cap) there was no EML.

So you don’t actually know then?

 

[geoffus]

My E250 had the low coolant warning come up twice last week, I didn’t bring up a EML at all, topping up with distilled water sorted it.
Have you physically checked the level ?
Is it possible to view the coolant temp via the cars hidden menu ?

 

[DSM10000]

So you don’t actually know then?

Clearly neither do you.

You keep insisting the OP has a problem with coolant level when he clearly stated in two posts it was low coolant temperature.

I have had many cars, not one, including Mercedes lit the EML with low coolant. All either gave a visual warning via a lamp (not the EML) or a message to check coolant

@geoffus above concurs with my experiences

 

[DSM10000]

My E250 had the low coolant warning come up twice last week, I didn’t bring up a EML at all, topping up with distilled water sorted it.
Have you physically checked the level ?
Is it possible to view the coolant temp via the cars hidden menu ?

Thank you for your clarification.

I haven't found coolant temperature reading in any menus. I can see it via my iCarsoft though.

 

[kianok]

Clearly neither do you.

You keep insisting the OP has a problem with coolant level when he clearly stated in two posts it was low coolant temperature.

I have had many cars, not one, including Mercedes lit the EML with low coolant. All either gave a visual warning via a lamp (not the EML) or a message to check coolant

@geoffus above concurs with my experiences

So pleased for you that someone supported your thoughts.

Not my experience of the issue though.

Hope that helps.

 

[DSM10000]

So pleased for you that someone supported your thoughts.

Not my experience of the issue though.

Hope that helps.

Neither helps nor hinders

EML warnings are almost exclusively related to emission issues either directly or indirectly such as O2 sensors values , NOx sensor values , Camshaft position sensor positions MAF values etc, not fluid levels.

There are other sensors that monitor those.