Diagnostic Aids

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill condition.

DTC P0446 Evaporative Emission (EVAP) Vent System Performance

Step	Action	Values	Yes	No
Schematic Reference: Evaporative Emissions Hose Routing Diagram
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Inspect the evaporative emission (EVAP) system for the following conditions: A damaged EVAP vent valve A damaged EVAP canister Did you find and correct the condition?	-	Go to Step 9	Go to Step 3
3	Turn OFF the ignition. Disconnect the purge line from the EVAP canister purge solenoid. Turn ON the ignition, with the engine OFF. Observe the Fuel Tank Pressure parameter with a scan tool. Is the Fuel Tank Pressure sensor parameter within the specified range?	-1 and +1 in H20	Go to Step 4	Go to Step 8
4	Turn OFF the ignition. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement . Remove the EVAP vent valve from the EVAP canister. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . With the EVAP canister removed from the vehicle, connect the EVAP vent valve electrical connector. Turn ON the ignition with the engine OFF. Command the EVAP vent valve ON and OFF with a scan tool. Does the EVAP vent valve open and close?	-	Go to Step 5	Go to Step 6
5	Remove the fresh air inlet cover from the EVAP canister. Inspect the fresh air inlet for a restriction or a blockage. Inspect the fresh air inlet filter for a restriction or a blockage. Did you find and correct the condition?	-	Go to Step 9	Go to Step 7
6	Replace the EVAP vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . Did you complete the replacement?	-	Go to Step 9	-
7	Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement?	-	Go to Step 9	-
8	Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement?	-	Go to Step 9	-
9	IMPORTANT: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results. Turn OFF the ignition. Connect all disconnected components. Connect the J 41413-200 Evaporative Emissions System Tester (EEST) power supply clips to a known good 12-volt source. IMPORTANT: The GE-41415-50 fuel cap adapter, may not be available for the start of production. Once the J41415-50 is available, start the diagnosis at the fuel fill cap. Install the nitrogen/smoke supply hose onto one of the following sources: Connect the GE-41415-50 to the fuel fill pipe, and the J 41413-200 nitrogen/smoke supply hose to the fuel cap adapter. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port. Turn ON the ignition. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 control panel to NITROGEN. Pressurize the EVAP system to the first specified value with the remote switch. Observe the fuel tank pressure sensor in H2O. Command the EVAP vent solenoid open with a scan tool. Is the fuel tank pressure sensor parameter less than the second parameter?	5 in H2O 1 in H2O	Go to Step 10	Go to Step 2
10	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK