I have an 04 5.4 lariat 4x4 and my CEL came on the other day. I had the code pulled and I was told that the coolant temp was not getting warm enough?? Is this a thermastat issue or something else?? any suggestions would be helpful thanks in advance..

 

What is the code?

 

its code 128..any help would be appreciated

 

P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature... The engine is not overheating but it does take a little while to warm up and my mileage sux...even worse than before...is it the thermostat? I have cleared it once before and the code came back...Thanks for your help

 

Could be thermostat stuck open or bad sensor.

 

bad sensor??

 

Go with replacing the thermostat first. cheap easy..

 

Yes. Cylinder head temp. Do Tstat first though.

 

I just read my manual on replacing the CHT...I really hope that this new T-stat fixes it..I really dont want to do all that work for a small a** sensor..

 

Just replaced my T-stat, the temp came up to about midway which hasnt happened in a little while so I am hopeful that this has fixed it...thanks for your help