Which condition may suggest that maintenance is required on the hydraulic system according to the reported hydraulic pressure?

The condition indicating that maintenance is required on the hydraulic system is no pressure available when the pump is stopped. This situation suggests a possible issue within the system, such as a leak, a blocked line, or a malfunctioning pump that prevents the establishment of pressure when the system is in a resting state. If the pump isn’t generating any pressure while it is stopped, it implies that the system isn't holding or maintaining hydraulic fluid, which is critical for proper operation.

In contrast, high pressure readings may indicate that the system is operating under strain but do not necessarily elicit maintenance unless they exceed safety standards. Fluctuations in pressure readings may signal some irregularities, but they could also be due to normal operation or transient conditions. A pressure increase during operation is typically expected as the pump engages and the system builds pressure, which would generally not indicate a problem unless accompanied by other adverse effects. Thus, the lack of pressure while the system is stopped is a clear indicator that maintenance is warranted.