P1456 Evaporative Emission Control System Leak Detected Small Leak

Possible causes

– Missing Fuel cap
– Incorrect fuel filler cap used
– Fuel filler cap remains open or fails to close
– Foreign matter caught in fuel filler cap
– Incorrect fuel tank vacuum relief valve
– Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve.

Tech description

Usually loose or bad fuel tank filler cap will triggered this codes. Retight fuel tank filler cap and erase code to repair problem. There are several service bulletins for this problem, if tighten the gas cap does not repair the problem, check for Service bulletins for your model year.

What about the obd code?

The P1456 code is detected when the EVAP system has a very small leak.

Symptoms

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

P1456 Description

This diagnosis detects leaks in the EVAP purge line using engine intake manifold vacuum. If pressure does not increase, the 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.

Most Nissan Models EVAP System Diagram