Q: P0443

Hi there. A P0443 code will set when the evaporative emission system performs a self test and activates the purge valve to use engine vacuum to pull a vacuum on the tank for leak testing. When the engine computer does not see the fuel tank pressure lower, it sets the P0443 code. This can be a purge valve, as you have replaced, or it could be a wiring issue or a system leak. A sure sign that the valve is getting a signal is to listen and feel the valve during operation; it will cycle on and off and sound like a clicking sound. A leak to the tank will prevent a vacuum from being achieved. A leak can be anywhere from the vacuum hose at the intake to the purge valve to the fuel tank or a failing gas cap could be allowing fresh air into the tank through the filler neck. Note that small rodents have been known to chew into the hoses of the evaporative emission system creating leaks. YourMechanic has several available technicians to assist you with a check engine light inspection and provide an estimate and direction of repair.