Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Possible a noticeable fuel odor caused by the release of fuel vapors

Possible Causes

- Missing or loose fuel cap - Incorrect fuel filler cap used - Fuel filler cap remains open or fails to close - Foreign matter caught in fuel filler cap - EVAP canister or fuel tank leaks - EVAP system hose leaking - Fuel tank leaking

When Detected

Malfunction is detected when EVAP control system has a very small leak, EVAP control system does not operate properly.

Tech Notes

The fuel tank filler cap and the Purge Volume Control Valve are the more common problems that will trigger the P0456 code on Infiniti vehicles. There is an Infiniti Service Bulletin to help diagnose the P0456 code: Infiniti OBDII Code P0456

Description

This diagnosis detects leaks in the Evaporative Emission (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition. The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.