phuthuvo

Hi all, My C300 has P0128 code, how do I know which part should I replace (Coolant Temp. Sensor or Thermostat?)
Thanks for your help

dbldpr

If you can afford it replace them all

phuthuvo

Thanks, I am going to replace Thermostat first to see if the CEL go off, if it is not then I will replace Coolant Temperature sensor.
BTW, do I need to drain coolant to replace just Coolant Temp. Sensor.
Much appreciated for you reply.

dbldpr

I have never had to drain the coolant to replace a sensor but I have not done it on a Mercedes so I am not sure

MJ50

moved to W204 forum...

louiet3

Had the same code pop-up 2 months ago after a temperature drop and for me it's the thermostat.

phuthuvo

Hi all,
I just replaced thermostat, it took about 2 hour, it is easy job for diy. I don't want to reset the OBD code, just leave it as it and try to drive for couple day to see if the P0128 code disappear.
BTW, I ordered thermostat and coolant from FCP Euro, CFP EURO give Life time warranty on their part, free shipping and no tax.

fritza2tt

Whoa! Don't rush into changing the thermostat, especially after an outside air "temperature drop". I had this problem a couple of days ago. It was cold, below freezing, and I started out driving slowly to give the engine a chance to warm up. After about a mile the "check engine" light came on. What I found out is that the CEL is a timed response to engine warm-up. If the engine does not warm up quickly, as it will with the thermostat closed, the computer only "thinks" that the thermostat must be stuck open. The thing to do is to check the actual engine temperature. If it warms up quickly it means the thermostat was CLOSED. And once it warms up and settles in the normal range, in my case between 75 and 85 Degree C, it means the thermostat is monitoring and maintaining normal engine temperature, just as it was designed to do.

DarkOps

HI phuthuvo, did the check engine light and the P0128 code disappear after replacing the thermostat? Was the thermostat the issue?

phuthuvo

It does not Check Engine light does not disappear, I have to clear it, you can use any cheap scan to reset, don't need to buy the expensive one

Zubair86

Class. W204 P0128 error Coolant Thermstat

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C Class. W204 P0128 error Coolant Thermstat

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#1
Zubair86 , Today 01:14 AM
Seen this post maybe u guys can advise

So I Got Error P0128 on my 2013 Mercedes C180 w204 face-lift. I had a diagnostics found out it could be faulty Thermostat or faulty ECT(Temperature sensor for Coolant)
​​​So I cleared the error.... I have monitored the gauge while the error was on and after I cleared it.
There are no issues.
It warms up to optimal temperature just like it always has.
Left it overnight
Took it for a test drive.. It's cooling just fine..
The error has not come back
Bare in Mind we have been it was a unusually HOT day.


My QUESTIONS is this.
What could have happened and should I be concerned.??
Could it have just been a sensor malfunction.
It's not overheating??
And if it was really a should the engine light not come back on after my test drive this morning