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MY2010 was throwing a p0128 code. Replaced the thermostat and erased the codes but the code comes back immediately after clearing. I'm going to go check to make certain I have the plug pushed into the thermostat but wanted to check if there are any other ideas. The CEL DOES NOT come on...maybe it needs more than one to turn the light on (when I cleared the codes there were three)
I filled up the reservoir with fluid but is there a bleed valve or technique to make certain that the air is out of the system?
I'm wondering if this has to do with 'emissions' and thus follows a different workflow than the average repair. Going to drive it around for a a few days then check the codes again.
My CEL cleared after a few starts. No valve, I change the coolant in the radiator every few years, I fill and run to operating temperature, then once it cools top up, repeat as needed.
Tpete19,
It certainly could be. I would think there would be a different code as the p0128 is a "not getting to operating temp fast enough". The thermostat is designed to fail in the open position so I can see why it points to replacing the thermostat. I'm not certain how a failing temp sensor would look ie: 0 reading or 100% reading. Would the temp sensor also be what drive the dash gage? The car reads about 85d at operating temp.
Thoughts appreciated.
SAVZ, Yes, the CEL was originally on. When I started there were (3) P0128 codes. Replaced the thermostat and then cleared the codes. I was able to clear 2 of the 3. The third goes away for a second but (with the car hot or cold) it comes back after the next read cycle (about two seconds).
I used the torque app to clear it, had it as current fault. Have you noticed any symptoms of a stuck thermostat before replacing it? Besides the code. Any difference now? My was taking forever to warm up, and would not go above 80c, around 60c in cold weather. Changing it solved that right away.
Only indicator was the CEL, no other symptoms other than she felt that the heater took longer to get hot.
Replaced the thermostat, cleared codes but P0128 would come back right away. Checked today and no more P0128...code is gone, all is clear.
I'm pretty certain it has to do with the code and emissions; if the car doesn't warm up fast enough it will pollute more.
Therefore the algorithm would require emission codes a longer period of time to sample the condition to make certain the problem is resolved OR force a reset from a better machine (STAR/Dealer).
Kind of like an airbag fault.
Hopefully this will help somebody from replacing too many parts if they have P0128.
Only indicator was the CEL, no other symptoms other than she felt that the heater took longer to get hot.
Replaced the thermostat, cleared codes but P0128 would come back right away. Checked today and no more P0128...code is gone, all is clear.
I'm pretty certain it has to do with the code and emissions; if the car doesn't warm up fast enough it will pollute more.
Therefore the algorithm would require emission codes a longer period of time to sample the condition to make certain the problem is resolved OR force a reset from a better machine (STAR/Dealer).
Kind of like an airbag fault.
Hopefully this will help somebody from replacing too many parts if they have P0128.
Code P0128 relates to the thermostat stuck open. Following is the code that I get:
Component Y110 (Three-disk thermostat valve) jams in opened position. : Coolant temperature rises too slowly. (P0128)
So I don't think it has anything to do with the emissions. I just wonder what is (Three-disk thermostat)
Coolant temp rising too slowly could certainly pop an emissions related code as the emissions systems don't operate optimally with a cold engine.
An air bubble in the system restricting flow or preventing the temperature sensor from getting an accurate reading can mimic a cool condition. As mentioned in a previous reply, full heat/cool cycles and topping off the coolant levels when cold can help purge the air from the system it if was allowed to run too low. Also, a thermostat failure is not unusual on a 10 year old vehicle.
I am working with a 2009 W211 E350 and Have a Check Engine Light and P0128 Code Read with my ODB-2 (Actron CP9175) Reader.
Purchased the Kit From FCPEURO
1 Thermostat & Housing with sensor
1 Upper hose recommended
1 gallon of coolant.
I replaced the Parts and still have a Check engine light on dash as well as the P0128 Code.
Will this go away within a day or two, is it an air pocket thing. do I need a new ODB 2 or Euro car reader.
or can I access the code and clear with the onboard computer and if so please advies.
Hey guys I’ve got a 2011 e550 4 matic, same thing happened to me. p0128 came up one day, I didn’t feel any negative symptoms but regardless went and replaced it the next day and the code was gone but got a new code for a misfire in cylinder 6, found a bad spark plug and replaced that and all is running fine so went to clear my codes but it looks like the P0128 is back but there are no symptoms or rough riding or anything. And my harness is plugged into the thermostat correctly. Did you guys figure out why the codes continues to come back even after replacing with a new MB thermostat from the dealer? Why did you do to solve this?
03-05-2018, 04:00 PM
