We've had our 2007 Prius for about a month. The other day we heard a rattling / squeaking noise coming from the passenger seat while we were driving. The volume of the rattling/squeaking varied at different speeds (loudest around 40 mph).

We did notice that the rattling/squeaking was not quite as loud if someone < 150 lbs. was sitting in the seat and there was no rattling/squeaking if someong >150 lbs. was sitting in the seat.

Has anyone else experieced this?

You must have a rattle snake and a mouse living under your seat. Take your car to your Toyota dealer and they will have them removed.

It sounds like one or more of the seat bolts might be loose. It happens and taking it to the dealer is a good option for a new car.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

I've got the same annoying noise out of my 2007 Prius!

I did notice it happens more when it is cold outside and if I press on the passenger lower side plastic of the seat near the door, it effects the noise (yes it is tricky doing this while driving).

I know for sure mine is not seat bolts. I think it is plastic rubbing on something, at least that is what it sounds like. But it really is getting annoying now.

Find a load and speed that replicates the noise. Then have another driver hold the car at the speed while sitting in the back seat, you identify the source. The auto stores sell a stethoscope that can be used to find a source.

Looking forward to your report.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Thanks for the tips & suggestions. It definitely sounds like plastic. It's noticeably louder when it's cold. But when I turn the heat on, it's not quite as loud.

I'll be bringing it in to dealer soon for first oil change and have them look at it.

Exactly! It happens on mine when it is cold also. I won't let a dealership touch my car, as every dealer that has in the past has screwed something else up.

As I said before when I press on the plastic side of the passenger seat the noise stops. So it is either that part or a part it connects to under the seat.

But I am glad I am not the only one with this issue. If we can isolate it to an certain part then this should others with the same problem.

I realize that this thread is really old, but this was driving nuts until i figured it out. It is the plastic piece that fits over the passenger seat hinge latch/spring. It is tricky getting the thing off without breaking more than one piece (which apparently one tab has to be broken).

Anyway, the problem that i found is that the part rubs in a few places. The obvious ones are anywhere you see plastic on plastic contact when you start analyzing how to take the darn thing off. The not-so obvious one that was my main culprit was that the ribs on the back side of the part were in contact with the hinge spring.

My fix was to simply put pieces of masking tape where the plastic on plastic rubbing was occuring, and to shave the plastic ribs down so that they were no longer in contact with the hinge spring.
Hope this helps someone and saves them their sanity!

I also discovered the noise came from that part as well. But I am not willing to break that tab to get it off. There must be a way to get it off without breaking it. If I have to break it then I wonder how much to replace it with a new part.