GMC Repair: Diagnostic code questions..., mr saunders, buick lesabre

Question
Mr. Saunders,
I have a 2001 Buick LeSabre Custom (3.8 engine), and my "Service Engine Soon" light is on.  I hooked up a scanner and got the following diagnostic codes:
P0128
P0404
P1404
I know that P0128 has to the with the thermostat, and the other two relate to the EGR valve.
My question:  If I replace the thermostat, and replace the EGR valve...will that fix both codes?  (Assuming, of course, there is not something much more serious way down deep in the engine.)  The car runs fine, but I'd like to stay ahead of problems.
Any suggestions, advice you can offer is greatly appreciated.
Warm regards,
David Gardner

Answer
the 0128 code is coolant below operating temperature which could mean that your thermostat is stuck open.

as for the EGR code...you can clean your EGR valve yourself to save some money. disconnect all electrical and vacuum connections. in a bowl or like container soak the EGR in carb cleaner. Do not submerge the electrical connections in the cleaner. after the 24 hour period has past use a small brush, toothbrush and/or pipe cleaner to clean the carbon deposits from the valve.

This will save you about 300.00 on the EGR valve.