A customer experiences low power assist during parallel parking and a growling noise from the pump. What is the most likely cause?

The most likely cause of low power assist and a growling noise from the pump during parallel parking is low power steering fluid. When the fluid level drops below the recommended level, the power steering pump can struggle to draw up sufficient fluid to operate effectively. This can result in reduced assistance when turning the steering wheel, which is particularly noticeable during low-speed maneuvers like parallel parking. Additionally, the growling noise from the pump often indicates it is working harder than normal to pull fluid, which can happen when air is introduced into the system due to low fluid levels.

In comparison, a loose power steering belt might reduce the effectiveness of the pump but typically would not directly cause the pump to make a growling noise. Similarly, restrictions in the power steering fluid cooler—internally or externally—may lead to issues with fluid flow or temperature but are less likely to cause an immediate drop in assist or the particular noises described in this situation. Thus, low power steering fluid is the most common and likely explanation for the symptoms presented.