Thread: SES P0128
View Single Post
      01-05-2013, 01:16 PM   #14
Second Lieutenant
ForTheD's Avatar

Drives: 2007 e90 335i 6MT (ZSP)
Join Date: Aug 2010
Location: Salem, OR

iTrader: (0)

Garage List
2007 BMW 335i  [0.00]
Originally Posted by fl0wmastr View Post
The thermostat is the #1 reason, but I also got this code when I didn't mix the coolant/water mixture right.
Too much water raises your freezing point and too much coolant lowers the flow rate of the fluid and triggers the code.
The slower fluid doesn't cool the engine as well. If you've already replaced the thermostat, I'd try flushing the coolant in the system.
When I flushed my system the code went away and never came back.

If that doesn't fix it, I'd replace the thermostat, coolant temp sensor, the water pump, and the expansion tank. Unless you know these have been replaced recently.
I just got the message that some one replied and I realized I never reported back. I changed the thermostat probably about 4/2011 and have not had the error since. I wish I would have thought of coolant flush first though, that would have been helpful for the forum to know.