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P1800 NISSAN - Variable Intake Air System Control Solenoid Valve Circuit

Possible causes
- Faulty VIAS control solenoid valve
- VIAS control solenoid valve circuit harness is open or shorted
- VIAS control solenoid valve circuit poor electrical connection
When is the code detected?
The VIAS control solenoid valve cuts the intake manifold vacuum signal for power valve control. It responds to ON/OFF signals from the ECM. When the solenoid is off, the vacuum signal from the intake manifold is cut. When the ECM sends an ON signal the coil pulls the plunger downward and feeds the vacuum signal to the power valve actuator. An excessively low or high voltage signal is sent to ECM through the valve
- Engine Light ON (or Service Engine Soon Warning Light)
P1800 NISSAN Description
When the engine is running at low or medium speed, the power valve is fully closed. Under this condition, the effective suction port length is equivalent to the total length of the intake manifold collector's suction port including the intake valve. This long suction port provides increased air intake which results in improved suction efficiency and higher torque generation.

The surge tank and one-way valve are provided. When engine is running at high speed, the Engine Control Module (ECM) sends the signal to the Variable Intake Air System (VIAS) control solenoid valve. This signal introduces the intake manifold vacuum into the power valve actuator and therefore opens the power valve to two suction passages together in the collector.

Under this condition, the effective port length is equivalent to the length of the suction port provided independently for each cylinder. This shortened port length results in enhanced engine output with reduced suction resistance under high speeds.
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