SES Help Please!!!

[bikerboarder]

I've got a 2004 XLT 4.0 SOHC. SES light came on. I erased it by pulling negative battery terminal. But then it comes back on after 30-60 miles of driving. I went to Advance Auto to get the code. It read: P0128 Coolant Temp Below Thermostat Regulating Temp.

Coolant levels are OK. Interior gauges all seem normal. No problems with drivability.

Where do I start? Change Thermostat? Possible other sensors involved? Can somebody please provide insight on this ASAP? I can fix anything when given the proper directions. Thanks for the help.

 

[joshwho44]

http://www.obd-codes.com/p0128
I would start there...

Someone correct me if I'm wrong, but I think you could also check to see if the thermostat is sticking open by feeling the radiator hose. It should not be getting any coolant flow until the engine is near operating temperature.

 

[bikerboarder]

Thanks

Thank you. That's a good start.

Does anyone know if this problem is associated with my floor heating not working properly. I get air, but not very powerful out of my floor ducts. My window defrost and dash vents work properly and throw hot air fine. Would a faulty thermostat cause improper floor heating, or is this a separate issue?

Thanks for the help. I greatly appreciate it.

 

[fordbluefamily]

Your thermostat is probably bad. I have had two go out on our 04. Same code, mostly the same symptoms. It doesnt have to be very far out of range to trip that code. Cheap and easy fix.

 

[bikerboarder]

Thermostat was it

Your thermostat is probably bad. I have had two go out on our 04. Same code, mostly the same symptoms. It doesnt have to be very far out of range to trip that code. Cheap and easy fix.

Yes sir. I took a stab at it and changed the thermostat with a Stant 195. $19.99 and $2.34 for a new O-ring. The engine is running a little hotter now according to the temperature gauge and the code doesn't appear to come back on. Easy fix- 3 bolts, some coolant spillage on my garage floor, added some distilled water back into the reservior (about a pint) to make up for my laziness of not "draining the coolant system" as instructed by the manuals. All is well for now...except for the suspension squeaks I've noticed when driving over speedbumps or when braking...but that's for another post.

Thanks for your help!!

 

[fordbluefamily]

Glad you got it. I did mine just like you did yours. Aside from the plastic housing, its an easy design to work with.