Can the DIC be used to read OBD-II codes on a 2004 Buick Lesabre?

https://www.yourmechanic.com/article/p0171-obd-ii-trouble-code-system-too-lean-bank-1-by-andrew-quinn
All codes are OBD II. You can google them fro your answer.

need to scann the car to code and repair problembefore reset light

There should be two OBD ports on this vehicle, one under the steering wheel the other is located by the computer unit under the hood. Attach an OBD reader or OBD II Reader (available to be borrowed from most car part stores) and read the code.

Buy yourself a OBD-II code reader, V-Checker (online) or one from Harbor Freight Tools. $50-ish range. This will let you read the stored codes and even reset the check engine light, useful when the problem has been solved. In general the Check Engine Light doesn't reset itself. The computer knows something is operating out of specifications, sets a fault code within the computer's memory and illuminates the Check Engine Light to let you know something "flipped" when it should have "flopped". (That last part if just an electronics technician's joke derived from a chip called a flip-flop, used here with jocularity to indicate a malfunction.)

No, you need a OBD-II scanner to read the codes, most auto parts stores do it for free.

probably just a thermostat issue. get it fixed soon because it could cause a blown headgasket. you can or should get you thermostat replaced during high milage "tune ups" with timing belt, spark plaus, fluid exchanges, etc. don't have to but you definitely will need to replace your coolant

Check engine light comes on when the computer detects a problem. You will need to have the code(s) retrieved using an OBD II scanner. Some auto parts stores still do this. Once the code(s) have been retrieved you can figure out what's wrong and how to fix it.

oh thats the change oil light expect it every 3500 to 4500 miles they glow.. you can usually reset it by holding down the trip button with the car off and then turn the key to the II position where everything lights up
so read me >>>>>
Buick Rainier 2004-06, Buick Rendezvous 2002-05 w/o (DIC) Driver Information Center
Turn the ignition to ON without starting the engine. Fully press and release the accelerator pedal three time in five seconds. If the CHANGE OIL SOON’ indicator flashes two times, the system is resetting. Turn the key to OFF, then start the vehicle. If the CHANGE OIL SOON indicator comes on and stays on for five seconds, repeat the procedure.
Buick Rainier 2004-05 wI (DIC) Driver Information Center
The DIC display is located on the instrument panel cluster above the steering wheel. The DIG buttons are located on the steering wheel. Press button with the gas pump symbol to display engine oil life. Press button with the arrow symbol to reset engine oil life display.
Buick Rendezvous 2002-06 wI (DIC) Driver Information Center
To reset Service Reminder Indicator, turn ignition on with engine not running. Press the MODE button until DIC reads oil life left hold SET to reset. Press and hold the SET button until 100% is displayed. You will hear three chimes and the change oil message will go out. If the CHANGE ENGINE OIL’ message comes back on when the vehicle is started, the engine oil life system has not reset. Repeat the procedure.

the service engine soon light means a fault has occurred in the engine or emission system's electronic controls, it has nothing to do with any service you did in most cases, there are over 150 problems that turn the light on, to find out what the problem may be go to any Kragen Auto or Autozone parts store and ask them to run a OBD 2 trouble code test, IT IS FREE. then post the code back here for us to look at, which is also FREE.