Hello,

I drive a 2010 GLK 350 (premium package) Mercedes. I'm having an issue with the coolant system it seems. The normal running temperature is 80C. But my engine seems to be running below that by 5-10C or so. The check engine light is on and I went to AutoZone to see what the diagnostic said and it reads....

P0128: COOLANT THERMOSTAT (Coolant Temp Below Thermostat Regulating Temperature.)

What do I need to do to fix this problem? Any help or advice would be helpful.

Also, my computer on my car is telling me that a "tire pressure monitor system" sensor is faulty. I'm guessing just one needs to be replaced but I'm not sure. What is the best / cheapest way to go about this issue? I really want no check engine lights or tpms lights on my sticking out.

Thanks!

Joe