A low pressure car lift can begin drifting down due to leaks in either the pneumatic system or the hydraulic system, since the load is being supported by a column containing both air and hydraulic fluid. Both pneumatic and hydraulic systems actually leak from the time they are new, because no pneumatic or hydraulic seal is perfect.

In a new, well-designed parking lift, the rate of fall relative to the amount of time the lift is extended for a typical repair is minimal and does not present a safety problem. In older lifts, seal bypass may be excessive and does present a safety problem. Hydraulic fluid may also leak from the bottom of the lift barrel into the ground. This type of leak is difficult to diagnose and repair.

Leaks in the compressed air system present a greater problem. The air line from the air control valve for the automatic parking lift is typically buried in the concrete floor of the shop or in the soil below the concrete. This air line is usually made from galvanized iron pipe. Leaks through the rusted walls of galvanized pipe allow the hydro-pneumatic system used in the lift to lose pressure. It is possible to imagine a case in which the weakened pipe wall at some point in the system could blow out when pressurized, resulting in the potential for a catastrophic accident. This situation will be mitigated with an appropriately designed orifice in the bottom of the plunger, so that the hydraulic fluid retards the rate of fall of the lift.

Low hydraulic fluid in the parking equipment can result in accidents. If the fluid level is below the orifice in the bottom of the plunger, the plunger can retract more rapidly, since air will pass through a hydraulic orifice faster than hydraulic fluid will. Dry seals are a common cause of a phenomenon called chattering in the hydraulic business, wherein the unlubricated seals allow jerky rather than smooth motion. Some lift designs incorporate a low level failsafe system. This is typically a float which moves with the hydraulic fluid level and which shuts off the flow of pressurized air to the cavity inside the plunger when the oil level is low.