P0128 with CEL light
Thread Starter
Junior Member
Joined: Mar 2019
Posts: 56
Likes: 2
From: North Valley, California
2014 Mercedes E63 AMG
P0128 with CEL light
just started the car yesterday morning and Check engine light came on......scan the car with my handheld and error code is P0128 "thermostat" temperture is too low on dashbroad error message too.
took the car to local benz dealership and tech did an diagnositic test and told me that my 2014 E63 amg s needs an ECU update. Anyone has this issue with P0128 that needs an ECU update and not replacing the thermostat?
I have extended warranty so just want to make sure they are fixing the problem and not brushing me off.....
took the car to local benz dealership and tech did an diagnositic test and told me that my 2014 E63 amg s needs an ECU update. Anyone has this issue with P0128 that needs an ECU update and not replacing the thermostat?
I have extended warranty so just want to make sure they are fixing the problem and not brushing me off.....
MBWorld Fanatic!
Joined: Apr 2008
Posts: 1,399
Likes: 202
From: Bay Area, California
2015 E63s AMG, 2020 GLC 43 AMG
It sounds like the tech just ran his diagnostic tool to see what codes came up to verify what you claimed and then saw that your ECU revision is out of date and said it should be updated. There is no harm in doing this. But I have no idea if, or how, it is related to a thermostat code. 2 separate things I suspect.
Let them update your ECU and watch to see that the CEL does not come back. Assuming you still have some time on your warranty.
Also, strongly suggest that if they are going to update your ECU firmware that they make sure the TCU firmware is also current.
Good Luck
Let them update your ECU and watch to see that the CEL does not come back. Assuming you still have some time on your warranty.
Also, strongly suggest that if they are going to update your ECU firmware that they make sure the TCU firmware is also current.
Good Luck
