Methods and apparatus for detecting a leak in a gas precharged hydraulic accumulator having an initial gas charge entail activating a hydraulic pump to charge the gas precharged hydraulic accumulator and the hydraulic circuit associated with the gas precharged hydraulic accumulator when the hydraulic circuit and the hydraulic accumulator have a temperature that is substantially equivalent to an ambient temperature, e.g., on a cold start. The hydraulic pressure in the hydraulic circuit is monitored, and when a step in the hydraulic pressure is detected, various quantities are measured and used to determine a volumetric efficiency of the pump for use in later calculations of remaining gas amount.