Preassure sa Gas Cap

[jick.cejoco]

cars compliant to OBD II are designed to pressurize the system after shutdown and a pressure sensor monitors the pressure if it stays for a predetermined time from a slow calibrated leak. the objective is to check the the integrity of the hoses, tanks and the pressure cap if there are any leaks and to illuminate the malfunction indicator light if there are leaks. the vapors are stored in the charcoal canister to be used as fuel as the engine warms up and the throttle is above idle position. the pressure cap is a compound cap, there is a pressure cap that prevents release of fuel vapors into the atmosphere and a vacuum valve to allow atmospheric pressure into the tank when the fuel level drops. if there is pressure when you open the fuel cap hours after shutdown, the evaporative emission system might be saturated or clogged up. see your competent technician