DTC Parameters

• 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.
• Engine load is less than 35 percent.
• MAP is less than 40 kPa.
• Battery voltage is more than 11 volts.
• ECT at engine start-up is 46-167°F (8-75°C).
• IAT is between 46-122°F (8-75°C)
• Long term fuel trim cells learned (if not learned, engine must run longer than 16 minutes and 45 seconds)
• Fuel level is 1.6-12.7 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 P0446 sets if fuel tank pressure indicates less than 1.30 volts (less than -6.00 in. H20) during phase "A" of the EVAP diagnostic system test or less than 2.02 volts (less than -2.41 in. H20) during phase "C" of the EVAP diagnostic test indicating a blocked vent system. Condition exists for 15 seconds for phase "A" or condition is present by the end of phase "C".

DTC P0446 diagnostic runs once during phase "A" and phase "C" of the EVAP diagnostic test once per ignition cycle. If the P0446 diagnostic fails, the ECM will rerun the EVAP diagnostic test from the beginning and must fail the P0446 diagnostic again to set the DTC. If an EVAP diagnostic test is aborted due to changing enable criteria, the ECM will run the entire EVAP diagnostic test up to three times per ignition cycle.