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Test Description

WARNING: This page is about a different car, the 2004 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 3:  This test determines if the failure is present or intermittent.
DTC P0446

Step
or		 Action Values Yes No
Schematic Reference:  Evaporative Emissions (EVAP) Hose Routing Diagram 
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 Inspect the evaporative emission (EVAP) system for the following conditions:
Did you find and correct the condition?		 - Go to Step 13  Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the EVAP purge pipe from the EVAP canister purge solenoid valve. Refer to Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement .
  3. Turn ON the ignition, with the engine OFF.
Is the fuel tank pressure sensor parameter within the specified range?		 -1 to +1 in H2O Go to Step 4  Go to Step 7 
4
IMPORTANT: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  1. Turn OFF the ignition.
  2. Connect the EVAP purge pipe.
  3. Connect the J 41413-200  Evaporative Emissions System Tester (EEST) power supply clips to a known good 12-volt source.
  4. Install the J 41415-40  Fuel Tank Cap Adapter to the fuel fill pipe.
  5. Connect the fuel fill cap to the J 41415-40  .
  6. Connect the J 41413-200  nitrogen/smoke supply hose to the J 41415-40  .
  7. Turn ON the ignition, with the engine OFF
  8. Command the EVAP canister vent solenoid valve closed with a scan tool.
  9. Turn the nitrogen/smoke valve on theJ 41413-200  control panel to NITROGEN.
  10. Use the remote switch to pressurize the EVAP system to the first specified value.
  11. Observe the fuel tank pressure sensor in H2O with a scan tool.
  12. Command the EVAP vent solenoid open with a scan tool.
Is the fuel tank pressure sensor parameter less than the second specified value?		 5 in H2O
1 in H2O		 Go to Diagnostic Aids Go to Step 5 
5 Disconnect the EVAP vent hose from the EVAP canister vent solenoid valve.
Is the fuel tank pressure sensor parameter less than the specified value?		 1 in H2O Go to Step 11  Go to Step 6 
6 Disconnect the EVAP vent hose from the EVAP canister.
Is the fuel tank pressure sensor parameter less than the specified value?		 1 in H2O Go to Step 9  Go to Step 12 
7 Test for poor connections at the harness connector of the fuel tank pressure (FTP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 8 
8 Test the low reference circuit of the FTP sensor for a high resistance or an open.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
9 Repair the pinched or restricted EVAP vent hose.
Did you complete the repair?		 - Go to Step 13  -
10 Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .
Did you complete the replacement?		 - Go to Step 13  -
11 Replace the EVAP canister vent solenoid valve. Refer to Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement .
Did you complete the replacement?		 - Go to Step 13  -
12 Replace the EVAP canister. Refer to Evaporative Emission (EVAP) Canister Replacement .
Did you complete the replacement?		 - Go to Step 13  -
13
  1. Turn OFF the ignition.
  2. Disconnect the EVAP purge pipe from the EVAP canister purge solenoid valve.
  3. Turn ON the ignition, with the engine OFF.
Is the fuel tank pressure sensor parameter within the specified range?		 -1 to + 1 in H2O Go to Step 14  Go to Step 2 
14
IMPORTANT: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  1. Turn OFF the ignition.
  2. Reconnect all disconnected components.
  3. Connect the J 41413-200  to the fuel fill pipe.
  4. Turn ON the ignition, with the engine OFF
  5. Command the EVAP canister vent solenoid valve closed with a scan tool.
  6. Turn the nitrogen/smoke valve on theJ 41413-200  control panel to NITROGEN.
  7. Use the remote switch to pressurize the EVAP system to the first specified value.
  8. Observe the fuel tank pressure sensor in H2O with a scan tool.
  9. Command the EVAP canister vent solenoid valve open with a scan tool.
  10. Observe the fuel tank pressure sensor in H2O with a scan tool.
Is the fuel tank pressure sensor parameter less than the second specified value?		 5 in H2O
1 in H2O		 Go to Step 15  Go to Step 2 
15 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List System OK
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