Code P0128
 

Hello,
I’m new to this forum. My wife has a 05 C230 Kompressor. The check engine light came on the other day.I pulled the code, P0128. It has something to do with a bad thermostat or sensor? The car runs fine, doesn’t over heat. One thing I’ve noticed is that the fan will kick in, sometimes, when the car is over night cold. The coolant level is fine. Any thoughts? Comments?

Thanks in advance for the help.

Claudio

Does the engine run cooler than normal? A weak thermostat could be the problem. The engine coolant temp sensor may be bad, however not likely. Engine oil may have contaminated the engine wiring harness. Is the fuel control unit running the latest software?

The engine seems to run at normal temperature, according to the gauge. The odd thing is how the electric fan kicks in at cold temps. I don’t know anything about the software for the fuel control unit. Is it supposed be updated frequently? and what does that have to do with the cooling system? The engine is very clean, no oil anywhere. Thanks alot for your input.

Claudio

I would clear the code and not worry about it unless it it trips again.

Well, I have cleared the code, once before, it came back after 20 miles or so. Just for kicks, I may just replace the thermostat.

Thanks
Claudio

That code does mean the thermostat is at fault.

Thank you sir!

Claudio

What are the odds of it getting stuck in the shut position causing it to over heat, I need to drive it for a couple of days before I can replace the thermo.

Thanks for your help!

Claudio