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brownjeff, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 13886
Experience:  ASE Certified Technician, 17 years experience, Dealership Certified, Service Manager for 15 years
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Mercedes-Benz Check Engine light OBD scan reveals code P0128

Resolved Question:

Check Engine light OBD scan reveals code P0128 (low coolant temperature) is the problem. I have noticed poor heater performance and low temperature gauge readings. My guess is the thermostat is not completely closing to allow coolant temperature to reach proper operating level. I plan on replacing the thermostat in my 06 E350 4matic. Is it fairly simple to do & why is the thermostat so expensive?
Submitted: 6 years ago.
Category: Mercedes
Expert:  brownjeff replied 6 years ago.
Hello and Welcome to JustAnswer,

My name is XXXXX XXXXX I am here to try and assist your with your question. You are describing a failing thermostat and it is more expensive than a typical thermostat as you replace the housing with it as an assembly. Not bad to replaced as in a good location to work on and the repair will take around 1 1/2 hours to complete it.
Customer: replied 6 years ago.
I can see 2 torx screws holding on housing. Are these the only bolts to remove? Does the coolant have to removed or can the level just be lowered and where is the location of the petcock? I found a thermostat & goose neck assembly for an 06 S350 for $35. Is this another animal all together?
Thanks Jack
Expert:  brownjeff replied 6 years ago.
The thermostat and goose neck assembly is what you need and what I am calling the thermostat and housing. I will attach the instructions on replacing it to help. As long as you lower the level of coolant below the thermostat that is as much as will be needed to get it out


Edited by brownjeff on 12/1/2010 at 3:00 PM EST
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