Toyota Corolla automobiles manufactured prior to 2009 use a hydraulic power steering assist system. The system makes turning the car's steering wheel easier, especially at low speeds. In order for the system to function properly, the hydraulic fluid must remain at the proper level. Checking the fluid is part of a basic maintenance program, and drivers should check the fluid level at least monthly, if not at each fill up. 2009 and later year model Corollas use an electric power steering assist, which doesn't require hydraulic fluid.
Ensure that the vehicle is either at operating temperature or cold. To reach operating temperature, you need to drive the car for approximately 20 minutes at highway speed. To check the fluid when cold, the vehicle needs to have been parked for approximately 5 hours. Checking the fluid under other conditions will give you an inaccurate reading.
Open the bonnet and locate the power steering fluid reservoir. It is a cylindrical, clear plastic tank, with a round cap marked "Power Steering." The reservoir's location will vary slightly depending on what year model Corolla you have, but is generally located on the driver's side, near the firewall.
Clean the outside of the reservoir, using a clean rag, so you can see the fluid level. If necessary, moisten the rag with water. Check that the level reaches the indicated marks for either "Hot" or "Cold," depending on the car's temperature. If the fluid doesn't reach the indicated marks, you need to add fluid.
Turn the cap counterclockwise to open it. Add enough fluid to raise it to the proper level. Check the vehicle's owner's manual for the proper type of fluid to use. Replace the cap.
Ensure that you thoroughly clean the cap and reservoir before opening, to prevent contamination of the fluid.