If the only change was for box 12 with a code of D, there is no reason to file an amended tax return.

What code was on the original W-2 and what was it changed to? 

@wl49 

It's box 12a Code D  on both the original and on the new one, it's just the amount that changes

Code D in box 12 lists the amount you had withheld for your retirement plan contribution. It could have an affect on your retirement savings contribution credit if you qualified for that. So, you may want to prepare the amended return to see if your tax changes, and if not you don't need to file it. 

If I didn't qualify for the retirement savings contribution credit is it safe to say I don't need to file an amendment? Thank you to everyone for your responses so far! My job offered me no suggestions for what to do. 

You don't need to amend as long as the wages in box 1 did not change and you don't qualify for the retirement savings contribution credit.