Possible causes

– EVAP control system pressure sensor
– Damage harness or connectors to the Purge Control Valve
– The valve circuit is open or shorted
– EVAP canister purge volume control solenoid valve may be faulty (The valve is stuck open)

Tech notes

It’s a very common problem with Infiniti vehicles. If the harness is not damage, it’s very likely that the problem is the canister purge volume control solenoid valve.

When is the code detected?

The canister purge flow is detected during the specified driving conditions, even when EVAP canister purge volume control solenoid valve is completely closed.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0443 INFINITI Description

This system controls flow rate of fuel vapor from the EVAP canister. The opening of the vapor by-pass passage in the EVAP canister purge volume control solenoid valve changes to control the flow rate. The EVAP canister purge volume control solenoid valve repeats ON/OFF operation according to the signal sent from the ECM. The opening of the valve varies for optimum engine control. The optimum value stored in the ECM is determined by considering various engine conditions. When the engine is operating, the flow rate of fuel vapor from the EVAP canister is regulated as the air flow changes.
The EVAP canister purge volume control solenoid valve uses a ON/OFF duty to control the flow rate of fuel vapor from the EVAP canister. The EVAP canister purge volume control solenoid valve is moved by ON/OFF pulses from the ECM. The longer the ON pulse, the greater the amount of fuel vapor that will flow through the valve.