how do I go about detecting what my problem is . Ive replaced my fuel cap with a new one.

Question

I've replaced my fuel cap and don't know where to go from their.

Answer 1

P0440 Evaporative emission control system malfunction

This code occurs when EVAP system is unable to maintain or achieve vacuum. Some of the cause or the main cause is the fuel cap, or any disconnected EVAP hose. If all the EVAP hose are properly connected and no ruptured EVAP hose The FTP (fuel tank pressure) sensor is faulty , what happens is if the FTP does not report the true condition of the tank pressure This sensor sit at the top of the fuel pump moduel.