M-Class (W164) Produced 2006-2011: ML280CDI, ML320CDI, ML420CDI, ML350, ML500, ML550

Coolant Temperature Sensor location

Old Oct 27, 2021 | 09:42 AM
  #26  
Liro's Avatar
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ML350 2010 bluetec
Thanks for replying Maj, as a scan tool, I am using Foxwell NT630, it reads 3 modules (transmission, engine and one unknown), it is very funny that I don’t get any code and no check engine light ON, it would be very easy if I get a code. These days that weather is getting colder, I see that happening very often when I stop on lights and I thought maybe the coolant temp sensor could be the problem, also I have been watching live data with that scanning tool when RPMs were 800 and in a moment I saw the engine/coolant temp signal disappeared for a second. thanks for the attachment, I will see and the mentions from the PDF, and update back. Regards
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Old Oct 27, 2021 | 02:27 PM
  #27  
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2002 ML 320 & 2006 ML500
When the eng. is ice cold, remove the cap and check the level. And also see that you have the proper coolant.
Attached Files
File Type: pdf
Coolant Level Check ALL..pdf (78.9 KB, 483 views)
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Old Oct 27, 2021 | 05:37 PM
  #28  
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ML350 2010 bluetec
Will do, thank you Maj for all the helpful attachments and the time. very appreciated.
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Old Oct 28, 2021 | 03:05 AM
  #29  
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2002 ML 320 & 2006 ML500
Originally Posted by Liro
Will do, thank you Maj for all the helpful attachments and the time. very appreciated.
You are welcome.
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Old Nov 25, 2021 | 08:03 PM
  #30  
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From: Bronx
ML350 2010 bluetec
Hello Maj,

Just would like to update on regarding the issue I was having on IDLE RPM's of 800, so today I did change the Coolant Temp Sensor and seems to be fixed the issue, I am getting 700 RMP's on idle all the time (except the first time engine start on cold). I will watch if that problem comes back and let you guys know.

I hope this will be helpful for other guys that will experience this IDLE problem,

Many thanks to Maj for the help,
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Old Nov 26, 2021 | 07:52 AM
  #31  
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From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Originally Posted by Liro
Hello Maj,

Just would like to update on regarding the issue I was having on IDLE RPM's of 800, so today I did change the Coolant Temp Sensor and seems to be fixed the issue, I am getting 700 RMP's on idle all the time (except the first time engine start on cold). I will watch if that problem comes back and let you guys know.

I hope this will be helpful for other guys that will experience this IDLE problem,

Many thanks to Maj for the help,
Your welcome.
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Old Dec 22, 2024 | 04:41 PM
  #32  
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How to replace coolant temperature sensor on a Merc A180 2014

Hi,
I received a P0128 error code on a Merc a180 (2014), I bought a new coolant temperature sensor but not sure where in the engine to replace the sensor. could someone please provide me an image of instructions on how to do it.
The car is from Australia, right side is the driver's seat.
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Old Mar 28, 2025 | 01:18 PM
  #33  
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2012 ml350
is this the same location on a 2012 ml350 gas engine? I'm getting a permanent code for p0128(coolant thermostat temp below thermostat regulating temp) and p008A(low pressure fuel system). I replace the thermostat housing and cant seem to find the temp sensor. what is the part number for the o ring for the radiator hose and inlet pipe that goes into the thermostat housing? mine leaked after the housing change both seals on the hose and the inlet pipe.

thanks for any info
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Old Mar 29, 2025 | 07:55 AM
  #34  
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2010 ML550 VIN WDC1641722A564750, 2010 B180
Originally Posted by BMnewbie
is this the same location on a 2012 ml350 gas engine? I'm getting a permanent code for p0128(coolant thermostat temp below thermostat regulating temp) and p008A(low pressure fuel system). I replace the thermostat housing and cant seem to find the temp sensor. what is the part number for the o ring for the radiator hose and inlet pipe that goes into the thermostat housing? mine leaked after the housing change both seals on the hose and the inlet pipe.

thanks for any info
Yes, location is the same.
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Old Jun 19, 2025 | 03:42 PM
  #35  
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2012 E350 Convertible
Originally Posted by Maj. Dundee



At the rear of the engine.
Maj. Dundee, I love the pic you posted for this problem.

In my case I have a 2012 E350 Cab with an M276.9-- I am wondering if that is the same location for the sensor on mine?

If so does the engine have to come out for replacement? Do I have to have small hands? I don't

Is this a common source of irritating small coolant leaks? Its a somewhat small leak but nonetheless. There is no visible evidence on the ground etc. I just have to keep checking the reservoir every couple days and I will see the level has dropped. And I do get a whiff of the coolant when I get out of my car after driving. Its clearly something on that side. There is no sign of water in the oil etc. I have no reason to suspect head gaskets. Engine and Trans performance is exceptional!

I have replaced EVERY other part but this. Literally: Radiator, all hoses, reservoir, thermostat housing, water pump, engine oil cooler! I did all this myself.

But now.... this is looking like I may not be able to get to this. And I am afraid to find out how much I am looking at to have my indie do the work. And all this is over a dinky lil O ring?

I hope to hear back from you and thanks in advance for any help/ input you can provide.

-Marc
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