P0128 CEL "coolant thermostat stuck open"
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Junior Member
Joined: Sep 2021
Posts: 72
Likes: 5
2017 C43 Coupe
P0128 CEL "coolant thermostat stuck open"
Hi all, I just bought a 2020 c63 and received a CEL for coolant thermostat, after doing research on the M177 I was told it would only be 3-4 hours of labor for coolant thermostat replace but shop is telling me 13 hours. Can someone confirm how much they paid or if 13 hours is reasonable for a 2020 c63 coolant thermostat replacement?
Super Member
Joined: Mar 2019
Posts: 600
Likes: 97
From: NYC area
2019 C63S Coupe
Hi all, I just bought a 2020 c63 and received a CEL for coolant thermostat, after doing research on the M177 I was told it would only be 3-4 hours of labor for coolant thermostat replace but shop is telling me 13 hours. Can someone confirm how much they paid or if 13 hours is reasonable for a 2020 c63 coolant thermostat replacement?
I have 2019 C63s coupe with M177 and somehow it was not included in this notification. Maybe an oversite or Covid where other vendors needed to be used for years 2020-2023.
. I would contact the MB Dealership regarding this issue.
This photo shows MB Dealership internal Service Package and as you can see besides the other issues covered it includes Ignition Coils for 15 years/150,000 miles.
So if you supply MB Dealership with your vin# it shows that the thermostat issue noted in the above letter should be included on any dealership internal memo.
Last edited by jj18; Jun 26, 2025 at 03:22 PM.
Member
Joined: Apr 2017
Posts: 185
Likes: 36
From: San Diego
C63S Coupe/CLA45
P0128
Just got the CEL for this on Friday the 13th. As a 2nd owner I never gotten the extended warranty letter so will that be an issue or they just look up the VIN? I already booked an appointment for next week but haven’t contacted my SA yet should I or still just bring it in for them to work on? Mine is a 2020 with 18,180k miles.
Senior Member
Joined: Dec 2025
Posts: 433
Likes: 37
From: Keep it simple - keep it OEM
AMG C63s Coupe
The mb warranty is deposited by VIN.
You as new owner do not get a seperate letter if car has owner change.
I get a card with a number & VIN or only VIN also a paper document. but i know the next owner dont need it but if a pre owner says warranty i would check this fact before i buy.( MB Used car guarantee)
You can ask your mb service man to go for sure.
If coolant thermostat has a problem - to change is no easy & fast fix.
I understand not exactly is there a problem now with your thermostat or is this a regular recall with exchange from MB ?
Is this word wide for all M177 engines or only US customers ?
what means internal service package ?
You as new owner do not get a seperate letter if car has owner change.
I get a card with a number & VIN or only VIN also a paper document. but i know the next owner dont need it but if a pre owner says warranty i would check this fact before i buy.( MB Used car guarantee)
You can ask your mb service man to go for sure.
If coolant thermostat has a problem - to change is no easy & fast fix.
I understand not exactly is there a problem now with your thermostat or is this a regular recall with exchange from MB ?
what means internal service package ?
Last edited by C63s_Jack; Feb 14, 2026 at 04:59 PM.
Super Member
Joined: Mar 2019
Posts: 600
Likes: 97
From: NYC area
2019 C63S Coupe
Just got the CEL for this on Friday the 13th. As a 2nd owner I never gotten the extended warranty letter so will that be an issue or they just look up the VIN? I already booked an appointment for next week but haven’t contacted my SA yet should I or still just bring it in for them to work on? Mine is a 2020 with 18,180k miles.
