Looks like it could be many things from a google search. When I let off the brakes I hear what sounds like a check ball dropping under the dash. I also noticed a whining sound in park which sounds like it's coming from the gas tank. Could this be an evap line?

 

The whine is your fuel pump and its normal for it to make noise. What rear brake do you have? drum or disc? could be you have a sticky brake shoe. I'd check out the brakes.. could also be your brake pedal is a little noisy..

 

It has 4 wheel discs.

 

Your code 1151 is bank 2 front Ox sensor is no longer switching.
That bank has an issue with either an air leak of an injector leaking fuel, on the engine.
Good luck.

 

Possible vacuum leak under there and UR heater door moving. It may be moving to defrost an low vacuum.

 

Might also simply be that the O2S21 has failed and needs replacing. The other noises are simply red herrings for the original question.

 

I replaced both front o2 sensors about a month ago. I hate to think one went bad already.

 

Then you should have said so...

Perhaps one is bad. Swap them, reset the PCM, and see if the fault moves to the opposite side.

 

Well the light went out a few days ago. I guess it fixed itself.

 

Did you reset codes when you replaced the sensors the previous month?

 

Yes I cleared the codes last month.