I have a 00 millie thats giving me and error code off a obd 2 code puller of P0173 fuel trim malfunction bank 2, i am unsure of what to do or check to stop this from occuring. i have gotten the code 3 days in a row just after start up. the first time i also got a p0170 code(same discription but for bank 1). the car slightly hesitates when initally pushing on the gas but once up and running it runs well. Any help would be greatly appreciated.

 

0170/73 are probably the most common codes on these cars. what you have is a vacuum leak. dunno about the 2.5, but the 2.3 has 21 feet of vacuum lines, and they are all tied together by these cheap plastic connectors. some are T shaped, some are Y shaped, and some are just a 2 end connector. over time, the plastic becomes brittle and breaks. then air gets in. at idle and low speeds, the intake system is at high vacuum. so a tiny leak will make the engine need more fuel to compensate. it cant, so it throws the code, the check engine lite comes on, and the pcm goes to stored default fuel/timing maps. at idle and low speeds, the extra air has a big effect on fuel. at high speeds and high rpms, the vacuum is almost none, so very little to no extra air comes in.
bottom line, you need to check all the T/Y fittings, and replace any broken ones. the best way is to just replace all the vacuum line and fittings. i went to brass instead of the plastic. but on the 2.3, replacing the vacuum lines is like 100 times worse.

 

Check you air intake hose. These are notorious on the Millenias.

-Sheldon.