DTC Parameters
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- EVAP purge solenoid is commanded to a certain duty cycle.
- EVAP vent solenoid is commanded off.
- Engine is at idle.
- Vehicle speed is zero MPH.
- Volumetric efficiency is less than 35 percent.
- Main relay voltage is more than 11 volts.
- ECT at engine start-up is 40-131°F (4-55°C).
- IAT is between 40-140°F (4-60°C).
- Fuel tank pressure must be -7.23-3.61 in. H2O to enable test.
- Long term fuel trim cells learned (if not learned, engine must run longer than 16 minutes and 45 seconds).
- Fuel level is 2.4-13.4 gallons.
- No ECT, EVAP purge solenoid, EVAP vent solenoid, fuel tank pressure, idle speed, HO2S, throttle actuator, TP sensor or vehicle speed DTCs have been set.
DTC sets if fuel tank pressure indicates greater than 2.94 volts (less than -7.23 in. H20) for 20 seconds during phase A of the EVAP diagnostic system test or greater than 1.57 volts (less than -0.37 in. H20) for more than 1.5 seconds during phase C of the EVAP diagnostic test indicating a blocked vent system.
The entire EVAP diagnostic test will take about 16 seconds to complete when no errors have been detected. If the P0446 diagnostic fails, the rest of the EVAP diagnostic test is aborted and not run again in the ignition cycle.
If an EVAP diagnostic test is aborted due to changing enable criteria, the ECM will run EVAP diagnostic test up to 10 times per ignition cycle.