Patent ID: 7086276

Claim:
A method of diagnosing an evaporative emission control system to determine if a leak is present in the system, the method comprising: sealing the system from external influences; monitoring a pressure level with in the system over a cooling period, the monitoring including: providing a temperature-compensated pressure sensor having a pressure sensing element and a temperature sensing element, coupling a processor to the pressure sensing element and to the temperature sensing element, and receiving, respectively, pressure and temperature signals therefrom, implementing logic by the processor for computing a temperature-compensated pressure on the basis of pressure and temperature measurements; computing the temperature-compensated pressure as a function of the pressure at a first point in time and the temperature measured at substantially the first point, and at a second point, in time, wherein the function comprises the expression: P c =P 1 (2 −T 2 /T 1 ) where P c is the temperature-compensated pressure, P 1 is the pressure measured at the first point in time, T 1 is the temperature measured at substantially the first point in time, and T 2 is the temperature measured at the second point in time; and indicating a potential leak condition through a comparison of the pressure level within the system and a given threshold.