The power steering fluid reservoir on a 2007 Saturn Ion is typically located
under the hood, near the firewall, and often has a cap with a power steering symbol (a steering wheel with a fluid drop). It's usually a clear or translucent reservoir so you can see the fluid level.
However, to be absolutely certain, I highly recommend checking your owner's manual. The manual will have a diagram showing the exact location and provide specific instructions. Improperly adding power steering fluid can cause problems.
