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.

A short to ground causing the EVAP canister vent solenoid valve ON will cause the valve to close. This will cause DTC P0446 to set.
The ECM uses the FTP sensor to detect the amount of vacuum pulled on the EVAP system during the leak diagnostic tests. Ensure that the fuel pressure sensor is not skewed by verifying the FTP sensor on the scan tool is between 1.30-1.70 volts with the ignition ON and the fuel cap removed.
Inspect the following for causes of a blocked vent system:
- The EVAP canister vent solenoid valve blocked or a stuck valve
- A vent hose plugged, kinked, or pinched
- The EVAP canister restricted

DTC P0446

Step	Action	Values	Yes	No
Schematic Reference: Evaporative Emissions Hose Routing Diagram and Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
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 canister vent solenoid valve-Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . A pinched EVAP vent hose A damaged EVAP canister-Refer to Evaporative Emission Canister Replacement . Did you find and correct the condition?	-	Go to Step 17	Go to Step 3
3	Turn OFF the ignition. Disconnect the EVAP purge line from the EVAP canister purge solenoid valve. Turn ON the ignition, with the engine OFF. Is the Fuel Tank Pressure Sensor parameter within the Specified range?	1.30-1.70 V	Go to Step 4	Go to Step 10
4	IMPORTANT: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results. Turn OFF the ignition. Connect the EVAP purge pipe. Connect the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST) power supply clips to a known good 12-volt source. See Special Tools . Install the GE-41415-50 Fuel Fill Cap Adapter to the fuel fill pipe. See Special Tools . Connect the fuel fill cap to the GE-41415-50 . See Special Tools . Connect the J 41413-200 (J 41413-100) nitrogen/smoke supply hose to the GE-41415-50 . See Special Tools . Turn ON the ignition, with the engine OFF Command the EVAP canister vent solenoid valve closed with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 (J 41413-100) control panel to NITROGEN. See Special Tools . Use the remote switch to pressurize the EVAP system to the first specified value. Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Command the EVAP canister vent solenoid valve open with a scan tool. Is the Fuel Tank Pressure Sensor parameter more than the second specified value?	0.50 V 1.30 V	Go to Diagnostic Aids	Go to Step 5
5	Command the EVAP canister vent solenoid valve ON and OFF with a scan tool. Do you hear or feel the EVAP canister vent solenoid valve click when commanded ON and OFF?	-	Go to Step 6	Go to Step 8
6	Disconnect the EVAP vent hose from the EVAP canister vent solenoid valve. Is the Fuel Tank Pressure Sensor parameter within the specified value?	1.30-1.70 V	Go to Step 13	Go to Step 7
7	Disconnect the EVAP vent hose from the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than the specified value?	1.30-1.70 V	Go to Step 12	Go to Step 14
8	Disconnect the EVAP canister vent solenoid valve. Probe the control circuit of the EVAP canister vent solenoid valve with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors . Does the test lamp illuminate?	-	Go to Step 9	Go to Step 13
9	Test the EVAP canister vent solenoid valve control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 11
10	Test for an intermittent and for a poor connection at the fuel tank pressure (FTP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 15
11	Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 17	Go to Step 16
12	Repair the pinched or restricted EVAP vent hose. Did you complete the repair?	-	Go to Step 17	-
13	Replace the EVAP canister vent solenoid valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . Did you complete the replacement?	-	Go to Step 17	-
14	Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement?	-	Go to Step 17	-
15	Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement?	-	Go to Step 17	-
16	Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 17	-
17	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 (J 41413-100) to the fuel fill pipe. See Special Tools . Turn ON the ignition, with the engine OFF Command the EVAP canister vent solenoid valve closed with a scan tool. Turn the nitrogen/smoke valve on the J 41413-200 (J 41413-100) control panel to NITROGEN. See Special Tools . Use the remote switch to pressurize the EVAP system to the first specified value. Observe the Fuel Tank Pressure Sensor parameter with a scan tool. Command the EVAP canister vent solenoid valve open with a scan tool. Is the Fuel Tank Pressure Sensor parameter more than the second specified value?	5 in H2O 1.30 V	Go to Step 18	Go to Step 2
18	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