Toyota Sienna intermittent power steering assist failure causing stiff steering wheel on Toyota Sienna

Submitted by Vehicle Owner · Jun 23, 2025
Published by RepairPal

Problem overview

Some Toyota Sienna owners report experiencing intermittent power steering issues, resulting in stiff steering. A common symptom of electric power steering failure is a noticeable loss of power assist while driving. Additionally, fluid leaks, indicated by puddles of power steering fluid under the vehicle, can lead to erratic power assist and steering difficulties. The electric power steering (EPS) system, while efficient, may face problems such as high current draw on the electric steering pump, causing voltage drops that affect steering performance. Specific EPS malfunctions, including CPU circuit errors and motor circuit relay issues, have also been reported to contribute to these power steering problems. Furthermore, some owners find that intermittent loss of EPS correlates with alternator failures, which can lead to voltage declines impacting the power steering system. It is recommended that affected owners seek a thorough diagnostic check from a qualified technician to identify and resolve the underlying issues.

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