fret buzz on my bass

It only happens on the 12th fret. Is there a way to fix it myself?

Try to figure out if that fret, the 13th, has less wear on it than the surrounding ones. If it does it might be a candidate for you to sand off a little of that fret.

Take a metal ruler and hold it against your fretboard. If the ruler rocks back and forth over the 13th fret, I think you have a high fret.

Examine the fret to establish that the bottom of the fret, the part that should touch the fretboard, is sitting on the wood. If not it needs to be pressed or hammered in...carefully.

If it is to be filed or sanded to be lower you want to protect your fretboard with a mask, and you really don't want any of the metal shavings to get to your pickups.

Raising your bridge will help, and is so much simpler, but the one fret thing makes me think of other possibilities I mentioned.

is there a buzz on the 12th fret with all the strings?

if so try adjusting your action using the truss rod.

if its only on one particular string you could try adjusting the action of that string at the bridge.

I recommend you give this a go before you start hammering or sanding down your instrument

Harley,
I don't think the truss rod is for that, or would even make a difference that close to the body.

I'm not in favor of starting to work on the problem fret with physical alteration unless there is some reason to believe that is the problem.

Also I'm assuming this is not a ridiculously expensive bass.
me

its with the A and D strings.

If it's the A and D I would say you need a bridge height adjustment on those strings. I would assume you would also get a buzz on the G if it were a problem with the fret or the trust rod. Loosen those strings and adjust 1/32 up at a time then tune up. If that doesnt fix it. adjust another 1/32. Do this one string at a time.