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Home >> Chevrolet >> 2001 >> Camaro Base, 2D Convertible, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 7 (Engine Control System Self-Diagnostics - 5.7L) >> Diagnostic Tests >> DTC P0446: Evaporative Emission (EVAP) Vent System Performance ("Y" Body) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2000 Pontiac Firebird, 2000 Chevrolet Corvette, and 2000 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Using scan tool, perform SERVICE BAY TEST for EVAP system. If vehicle passes service bay test, fault is intermittent. See DIAGNOSTIC AIDS . If vehicle does not pass the service bay test, go to next step.
  3. Turn ignition off. Remove fuel tank cap. Turn ignition on, with engine off. Using scan tool, monitor fuel tank pressure sensor voltage. If sensor voltage is less than 4 volts, go to next step. If sensor voltage is not less than 4 volts, diagnose using DTC P0453 test. See DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT HIGH VOLTAGE ("Y" BODY) .
  4. Using scan tool, clear DTCs. Install fuel tank cap. Start and operate engine at idle. Using scan tool, command EVAP purge solenoid to 50 percent. Monitor fuel tank pressure. If pressure changes when solenoid is enabled, go to step  6. If pressure does not change when solenoid is enabled, go to next step.
  5. Remove fuel tank pressure sensor from fuel tank. Connect vacuum pump to fuel tank pressure sensor vacuum port. Apply 10 in. Hg to pressure sensor. Using scan tool, monitor fuel tank pressure sensor. If pressure changes as vacuum is applied, go to next step. If pressure does not change when vacuum is applied, go to step  13.
  6. Check for improperly routed, kinked or damaged EVAP purge and tank vent lines. Check for damaged EVAP component(s). Repair as necessary. After repairs, go to step  14. If no problem is found, go to next step.
  7. Check for kinked, pinched or damaged lines. Check for damaged "O" rings. Using scan tool, clear DTCs. Turn ignition off. Disconnect fuel tank vapor and EVAP purge line from EVAP canister. Plug canister port of fuel tank vapor line. Connect vacuum pump to EVAP purge line canister fitting. Turn ignition on, with engine off. Using scan tool, command EVAP vent valve on (closed). Apply 5 in. Hg to canister. If vacuum drops when EVAP vent valve is opened, go to step  10. If vacuum does not drop when EVAP vent valve is opened, go to next step.
  8. Leave system connected as from previous step. Disconnect and plug vent line at EVAP vent valve. Apply and hold 5 in. Hg. Remove vent line from EVAP vent valve. Observe vacuum gauge on pump. If vacuum drops when plug is removed, go to step  12. If vacuum does not drop when plug is removed, go to next step.
  9. Check EVAP vent line from canister to EVAP vent valve for restriction. Repair as necessary. After repairs, go to step  14. If no restriction is found, go to step  11.
  10. Repair restriction between fuel tank pressure sensor and EVAP canister. After repairs, go to step  14.
  11. Replace EVAP vent valve. After replacing vent valve, go to step  14.
  12. Replace EVAP vapor canister. After replacing canister, go to step  14.
  13. Replace fuel tank pressure sensor. After replacing sensor, go to next step.
  14. Using scan tool, perform EVAP system service bay test. If EVAP diagnostic passed the service bay test, go to next step. If EVAP diagnostic did not pass service bay test, go to step 3.
  15. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
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