Is it possible that a new sensor would be defective??

Question

Got a ford OBDII code p 1131. Checked for vacum leaks and stuck EGR valve. replaced a hose and pcv valve the light came back on a second time after code was cleared. Replaced o2 sensor with new one . Cleared codes drove truck to work , about 11 miles and no check engine light. Drove back home and light came back on (1995 ford ranger 4.0 engine) .

Answer 1

P1131 Lack of 02 sensor switching , indicates lean

There are 2 main sensor that will cause P1131, A contaminated MAF (mass air flow), just do a MAF cleaning,and low fuel pressure, the specification for fuel pressure are KOEO (key on engine off) 35-45psi, and key on engine running is 30-40 psi.