The sooooo called "Swirl control valve" on most Nissan Sentra's depending on your geog.. Loc..(ca. Especially) looks quiet differently
From even one year apart hince, your region of the country.
None the less, the power actuator is located at the driverside intake.
It is mounted with usually brass colored bracket onto the intake.
Its primary function is to monitor/maintain "Air-2-fuel" stricly governed
By the vehicles ecm.
Trouble code P1138 means: Swirl Control Valve Control Performance
swirl valve is located cloce to throttle body has two vacuum tubes
Swirl Control Valve Control Vacuum Switch
swirl control valve problem.
P1131 swirl cont sol/v
P1131 - Manufacturer control fuel air metering - Swirl Control
swirl control valve/solenoid control valve malfunction
P1130 code which reads something like "Swirl Control Valve Solenoid Control"
It's buried up under the intake manifold collector and has 2 (two) vacuum hoses and an electrical (probably lime-green) connection. The fix: remove and replace
That "swirl" in the hair, which is usually located near the crown area of the head, is known as a growth pattern or a "cowlick."
Swirl Control Solenoid Valve
Sounds like a swirl control solenoid problem. Its a Nissan only part and its expensive! $500-$800 job