In the latest Sienna models, power steering is electric and there is no power steering fluid to check. Older Sienna generations (1997–2020) used hydraulic power steering that requires fluid.
What changed: EPS vs hydraulic PS
The Sienna's steering system evolved with the 2021 redesign. The current generation uses electric power steering (EPS), while earlier generations used hydraulic power steering (HPS). The presence or absence of a fluid reservoir is the clearest indicator of which system your Sienna uses.
Electric power steering: 2021–present
In the 2021 redesign and subsequent model years, Toyota switched to EPS. The steering assist is provided by an electric motor controlled by sensors and a computer, not by a hydraulic pump and fluid. As a result, there is no dedicated power steering fluid reservoir or routine fluid maintenance for the steering system. If you experience steering issues, the cause is more likely related to the EPS electronics, battery health, or steering components rather than a fluid level.
Hydraulic power steering: Pre-2021 models
Earlier Sienna generations used a traditional hydraulic power steering system that relies on steering fluid. These models have a power steering fluid reservoir, hoses, and a pump driven by the engine. Regular maintenance typically involves checking the fluid level, looking for leaks, and using the fluid recommended in the owner's manual (often Toyota Genuine Power Steering Fluid or appropriate ATF, depending on year).
For older Siennas with hydraulic power steering, here are key maintenance considerations.
- Check the power steering fluid level regularly, especially after leaks or maintenance. The dipstick or reservoir cap will indicate the proper level.
- Inspect for leaks around the reservoir, lines, and pump; red or pink fluid in the service area often indicates PS fluid.
- Listen for whining, groaning, or squealing noises when turning, which can signal low fluid or a failing pump.
- Use the fluid type specified in your owner's manual; do not mix with other fluids; if in doubt, consult a Toyota service center.
These steps help maintain hydraulic PS systems and prevent steering stiffness or pump wear in older Sienna models.
What to do if you're unsure which system your Sienna has
Identify the system by checking the engine bay for a PS fluid reservoir and pump (hydraulic) or by noting the absence of such a reservoir and the presence of an electric steering motor near the column or rack (EPS). You can also verify by model year or VIN with a dealer or the owner's manual.
Summary
The answer turns on model year: 2021 and later Siennas use electric power steering with no power steering fluid to check; older Siennas use hydraulic power steering that requires a PS fluid. If you own an older model, follow PSF/ATF maintenance guidelines; if you own a newer model, focus on EPS diagnostics and battery health. Always consult the owner's manual or a Toyota technician for the exact fluid specifications and service procedures.