For 1990-2009 cars

The evaporative emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The function of the EVAP vent solenoid is solely for EVAP leak diagnostics. Outside air flows around the normally open valve, except during portions of the EVAP diagnostics, through the EVAP canister to the fuel tank. This allows the fuel tank to be at atmospheric pressure, around 101 kPa. The powertrain control module (PCM) controls the EVAP vent solenoid by controlling an internal driver that pulls the solenoid circuit to ground. The EVAP vent solenoid circuit is monitored for low and high voltage faults. DTC P0447 sets when the EVAP vent solenoid is commanded OFF and the feedback voltage at the PCM is low.

### DTC Parameters

DTC P0447 will set if EVAP vent solenoid feedback voltage is less than 1.25 volts with EVAP vent solenoid commanded OFF when:

• | The condition exists for longer than 0.5 seconds.

• | The ignition is ON.

DTC P0447 diagnostic runs continuously with ignition ON and EVAP vent solenoid commanded OFF.

DTC P0447 is a type D DTC.

### Diagnostic Aids

To locate an intermittent problem, use a scan tool to monitor the EVAP VENT - LOW VOLT or EVAP VENT - OPEN test with ignition ON, engine OFF. When a fault, open or short to ground exists, the scan tool will display TEST FAIL for both tests.

The tests will fail only when the device is being commanded OFF and the voltage at the PCM is low. The tests update every 100 ms whenever the ignition is turned ON and the device is being commanded OFF via the scan tool or PCM.

The EVAP vent solenoid resistance is 15-35 ohms.