Circuit Description

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.

PCM tests the EVAP system for large and small leaks, excess vacuum, purge flow during non-commanded conditions, fuel level and fuel pressure sensor faults, and EVAP purge and vent valve faults.

PCM monitors the fuel tank pressure sensor in order to determine the level of vacuum/pressure in EVAP system. PCM commands both EVAP purge solenoid and EVAP vent valve on when conditions for running this DTC are met in order to apply engine vacuum to EVAP system.

PCM commands EVAP purge solenoid off once system has reached a predetermined level of vacuum. This test checks if vacuum can be achieved in EVAP system. Failure to develop a vacuum may be caused by a large leak or restriction. This DTC sets after twice failing this test. DTC will set when EVAP cannot develop a vacuum greater than a predetermined value.

For duplication of DTC, ensure:

DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0420, P0430, P0500, P0502, P0503, P0562, P0563, P1120, P1220, P1221, and HO2S related DTCs are not set.
Ignition voltage is 10-18 volts.
BARO pressure is greater than 75 kPa.
Fuel level is 15-85 percent of full capacity.
ECT and IAT is 39-86°F (4-30°C).
Start-up engine coolant and intake air temperatures are within 16°F (9°C) of each other.