on my way to work this morning and as i exit the freeway my ses light comes on. it's dark out and so i wait to hook up the tuner to read the code. about 30mins ago i checked it out and the code was p0128.

p0128 - insufficient ambient temperature (ect) engine coolant temperature

could someone let me know what this means. i changed out my waterpump new year's weekend and switched out my t-stat to a 180* t-stat. i am in the process of replacing the fan clutch too.

 

could just be the engine temp sensor on the block.. probably not a big deal. You arent overheating or anything are you?

 

I just had that code on my wife's 02 grand prix. The thermostat was staying wide open. It would not even build up past 180*. I had just put a new waterpump and thermo so I guess it was a faulty one. It also took about 400 miles to recognize and to trip the SES light.

 

no, it's not over heating at all. the gauge stays right in between 160 and 210.

 

i don't have a way to log my coolant temps so i can't say what they are actually reading. i just know that the gauge stays right in between the 160 and 210 marks. i felt like that was odd since a lot of people that put 180* t-stats say their temps don't change. just like you, it has taken about 400-500 miles for the ses light to come on so i am not really sure what it could be.

could my problems be from my programmer not agreeing with the 180* t-stat?

 

Not sure if this will help or not, but it looks informative

http://gearchatter.com/viewtopic9378...b600a180b44980

 

Maybe the t-stat is stuck open, or could there have been an air pocket and the coolant is low? There's also a possibility that the coolant temp sensor got some debris (such as RTV, etc.) on it, giving the PCM false readings.

 

how can i tell if the t-stat is stuck open? the coolant doesn't look low and i thought that i got all the air out of the system.

 

squeez that upper tube to move the fluid around and you should be able to hear that little metal ring on the thermo moving around... if its stuck open than i dont think it'll make that sound.... well at least it didnt make that sound when mine was stuck open

 

did you do this with the motor running?