Please help me,

I have a 2000 v6 , just purchased it, gotta get it to pass smog

Getting engine code p1401 which i searched and found it as the dpfe sensor, so i bought a new one at autozone for $49.99 .

I replaced the dpfe sensor, and I am still getting the same code.

I reset the computer by leaving the battery cable off all night, starts up fine, no check engine light, then when i shut the car off and on, it reappears.

Tried resetting it again, same thing..

anyone know what else this could be since its not the dpfe sensor?