Same thing happened to me ....stuck open (which is better than the alternative). You are correct, it only comes in the housing so it is pricey. I bought the Motorcraft part, I didn't want to use aftermarket.

 

My manual is dated 12/2008 and doesn't list what you state. My dealer shop foreman told me, they don't use books just online as things are changed all the time. This might be one example of that happening.

Did you actually try to find anything in the PC/ED Manual about this T-stat monitoring?

Excuse me, I have my sensors crossed. You can have both but engines that don't have a MAF use a MAP and are more difficult to troubleshoot.

The MAP sensor isn't part of the EGR system but is used to diagnosis EGR operation.

 

Maybe one reason your manual doesn't list what I state is because we are talking about the '09 Escape Hybrid, Mariner Hybrid PC/ED Manual and not the regular Escape PC/ED Manual. Page 1-22 Manifold Absolute Pressure (MAP) says " The MAP sensor is part of the EGR system" word for word. It may be because we are dealing with a Atkinson Cycle Engine to determine how much exhaust gases is introduced into the intake manifold. We are not talking about engines that don't have a MAF sensor that are more difficult to troubleshoot, we are talking about the FEH.

Yes, on page 1-95 "Enhanced Thermostat Monitor" the manual describes how and when this monitor works. Without quoting the entire section, here is the results of a stuck open thermostat word for word:

"If the engine cooling temperature is too low, the thermostat may be stuck open and a DTC PO128 sets".

Gary

 

You are correct, there is a different manual for the FEH.

In mine for the MAP is states this and nothing more: The MAP sensor measures intake manifold absolute pressure. The PCM uses information from the MAP sensor to measure how much exhaust gas is introduced into the intake manifold.

In the ERG section it states that the MAP is used for EGR correction. Maybe you could say that the PCM is also part of the EGR system as well.

The section on components even mentions a ECT sensor but I know there is no ECT sensor input listed for the PCM. If you have the electrical diagram book, does it list a ECT input?

Gosh, the manual just flopped open to a page showing Enhanced Thermostat Monitor. It uses the IAT sensor, rpm, vehicle speed and engine load to predict engine coolant temperature. There's a good paragraph of details of how/when it compares info to determine if it's stuck. So it may have been new on the Hybrid, it wasn't on the gas version or the What's New List is wrong.

 

No harm done Bill. Did you consider that the gas Escapes may have had the Enhanced Thermostat Monitor before the '09 FEH? Maybe that's why you didn't see it added in the '09 Gas Escape PC/ED Manual in the "What's New" section.

Gary

 

Yes, that's what I stated in the last sentence of my post. It isn't an added sensor just added programing.