Faulty vacuum cut valve bypass valve solenoid (internal open or short circuit, or stuck valve); Damaged, chafed or corroded wiring to the valve; Poor connection at the valve connector or engine control unit connector (loose pin, corrosion, water ingress); Blocked, split or disconnected vacuum or EVAP hoses connected to the valve; Blown fuse or fault in the valve power supply; Fault inside the engine control unit driver circuit.

P1490

Vacuum Cut Valve Bypass Valve Circuit.

Nissan
Powertrain
Manufacturer code
Low severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
4: AreaAuxiliary emission controls
90: FaultThe specific fault in that area

What it means

On Nissan, P1490 relates to the circuit for the vacuum cut valve bypass valve, a solenoid in the evaporative emission (EVAP) system. The engine control unit commands this valve and monitors its circuit. It has seen an open circuit, short, or a response that does not match the command, so it has stored the code. Exact valve location and test values vary by model and engine, so confirm them in the model-specific service information.

Symptoms

Malfunction indicator lamp on
Possible fuel smell around the car or fuel filler area
Difficulty filling the tank or the pump clicking off repeatedly
Failed emissions or inspection readiness test
Often no noticeable change in how the car drives

Possible causes

Faulty vacuum cut valve bypass valve solenoid (internal open or short circuit, or stuck valve)likely
Damaged, chafed or corroded wiring to the valvelikely
Poor connection at the valve connector or engine control unit connector (loose pin, corrosion, water ingress)possible
Blocked, split or disconnected vacuum or EVAP hoses connected to the valvepossible
Blown fuse or fault in the valve power supplypossible
Fault inside the engine control unit driver circuitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data; check for other EVAP codes that point to a shared cause
Look up the valve location for the specific model and engine, then inspect its connector, wiring and nearby hoses for damage, chafing, corrosion or heat damage
Check the relevant fuse and confirm the valve has a power supply with the ignition on, following the wiring diagram
Measure the valve solenoid coil resistance and compare it with the specification in the service information
Use a scan tool active test, if supported, to command the valve and listen or feel for it operating
Check the wiring between the valve and the control unit for continuity, short to earth and short to supply
Inspect the connected vacuum and EVAP hoses for cracks, blockages or disconnections
Clear the code, road test and recheck that it does not return

How to fix

Replace the vacuum cut valve bypass valve if its coil or operation is out of specification
Repair or replace damaged wiring and terminals in the valve circuit
Clean, reseat or repair the connector at the valve or control unit
Replace split, blocked or disconnected vacuum or EVAP hoses
Replace the blown fuse after finding and correcting the cause of the overload
Only after all other causes are ruled out, diagnose and repair or replace the engine control unit

Can I keep driving?

Low severity

The car can normally be driven as usual, as this is an emissions-system circuit fault. Book it in soon, particularly if you smell fuel or need an emissions test, as an EVAP fault can leave fuel vapour venting.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.