Possible causes

– Faulty VVEL Actuator Motor Relay
– VVEL Actuator Motor Relay harness is open or shorted
– VVEL Actuator Motor Relay circuit poor electrical connection
– Faulty VVEL Control Module
– Faulty Engine Control Module (ECM)

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1091 NISSAN Description

VVEL (Variable Valve Event & Lift) is a system that controls valve event and valve lift continuously. Rotational movement of the drive shaft equipped with eccentric cam is transmitted to output cam via the rocker arm and two kinds of links to depress the intake valve. The Engine Control Module (ECM) decides the target valve lift according to the driving condition and sends the command signal to the VVEL control module. The VVEL control module controls the rotation of the control shaft using the VVEL actuator motor and changes the movement of the output cam by shifting the link supporting point. As a result, valve lift changes continuously to improve engine output and response.
Power supply for the VVEL actuator motor is provided to the VVEL control module via VVEL actuator motor relay. VVEL actuator motor relay is ON/OFF controlled by the VVEL control module. In addition, when the VVEL actuator motor relay cannot be controlled by the VVEL control module for some reason, it ON/OFF controlled by ECM.