P1490 Code failures by brands


Description of DTC code P1490

The EVAP System (Evaporative Emission Control System) stores the vapors resulting from the combustion process. The purpose is to avoid they cannot be expelled into the atmosphere. In parallel with the purge line of the EVAP system, the vacuum shut-off valve and the bypass solenoid valve are installed between the fuel tank and the EVAP container.

The vacuum shut-off prevents the vacuum can be applied from the intake manifold to the fuel tank. The bypass valve is a solenoid type, which is usually closed. It is only opened for onboard diagnostics. The bypass valve responds to the signals sent by the ECM (Engine Control Module). When the ECM provides an ignition signal (ground), the valve opens. It bypasses to apply the vacuum from the intake manifold to the fuel tank.

The P1490 OBDII fault code is set on Nissan and Infinit vehicles when the ECM receives a voltage signal from the EVAP vacuum shut-off valve bypass solenoid that is not within the established parameters.

Symptoms of fault code P1490

  • Check Engine light ON.
  • Lower fuel efficiency.
  • Irregular motor operation.

Causes of OBD2 P1490

OBD2 DTC P1490 is set for one of the following reasons:

  • The vacuum shut-off valve bypass solenoid wiring may be damaged.
  • The solenoid vacuum hoses may be clogged.
  • The bypass solenoid may be faulty.

Possible solutions of the DTC code P1490

To troubleshoot the P1490 OBDII diagnostic code, try this:

  • See TSBs.
  • Check the vacuum shut-off valve bypass solenoid circuit for damage to its wiring or connectors. In case you find common deficiencies as a result of corrosion, burns, or wear, make the respective corrections.
  • With the proper tools, read the shunt solenoid circuit voltages and verify that they do not indicate a short or open circuit. If you find inconsistent voltages, make corrections.
  • Check the condition of the vacuum hoses related to the bypass solenoid. If you detect blocked or clogged conditions, make the appropriate adjustments.
  • If after performing the above checks you still get the P1490 code, there may be a bad solenoid that needs to be replaced.


Codes related to P1490

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