Hey all, I just got this code while driving this morning. Thanks to Maximum4X4 and his 6.4 archives, I was able to look it up

P-0128 This error occurs when the ECT sensor signal indicates a coolant temperature lower than the operating temperature of the thermostat for an extended period of time.

What does this mean? I understand the condition but I guess my engine water temp remained cooler than it should thus the thermostat was never going to open? Or, is it stuck open? Some of you have had t-stats pretty much fall apart, right?

 

what is your water temps and egt's? If the EGT's

 

If you are drive a steady speed, say 50 mph, eng up to operating temps, flat road. Does your egt's stay steady as well? What is the eng temp's during this test as well?

 

Scott, I'll get back to you with precise numbers.

I think, driving flat road, unloaded, 50mph my egt is between 400-550. Coolant temp this morning never rose above 180. I just ran to the store to get some coffee when the code came up.

More info coming............

 

I am thinking it is just the thermostats but having just a little more info so we can rule out a sensor as the issue.

Did you clear the code and see if it comes back. I would do that as well. I understand those thermostats are a bit of a bear.

 

Check the Engine Oil Temp too on your Insight...I think I read on one of the TSBs where the oil temp should be within 8-10 degrees of the ECT...if the oil temp is where it should be (around 190?), but water temp isn't, I would say sensor may be bad (The coolant temp shouldn't be far from the water temmp, right? Since the only thing separating them in the engine block...)

 

Ok, went to the dealer and spoke with the diesel tech. Just stuck open tstat, nothing more. He said it's pretty common and that it is not an immediate concern because it usually frees itself on its own. No problem with waiting a couple days for the new part, no need to park the truck as long as I monitor things closely.

My coolant temp has been 175-190 but I am driving lightly, I'm home so I am not towing anything and the roads here are all 55, 45, and 35 mph, no interstates.

At 55 mph, my egt is 630 on flat ground, unloaded and doing my best to not be coasting or gaining speed with the throttle. rpm's are around 1350 or so.

Paul (the tech) cleared the code, checked the parameters and said everything is fine, I was looking at his laptop too and he showed me the vitals. He told me to wait and see if it happens again. I told him that I have the ESP and if he wanted the work it would be a warranty claim, he jumped all over it and we will get the new tstat early next week.

Oh, the oil temp is where it should be, right behind and with the water temp.

And, as luck would have it, there is a black 2011 F250 diesel Lariat with the FX4 package and all the bells on the lot just in case I feel the need to trade! Sticker was $60K!!!!!

If anybody out there is looking for a black one, it's Ballentine Ford, Greenwood, SC. The folks are good people and I would be glad to introduce any of you to my buddies over there.

 

Sounds good. I was wondering what your water temps were. they should be around 195 so that confirms the open t-stat.

Since it is not winter that will be fine.

Wonder just how hard it is to get in there to do the job on your own.