Circuit Description

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

PCM monitors the amount of vacuum in EVAP system by monitoring the fuel tank pressure sensor. For this DTC, PCM turns on both the EVAP purge and vent valves when conditions for setting this DTC are met. Engine vacuum is applied to closed EVAP system, checking whether vacuum can develop in EVAP system. Failure to develop vacuum may result from a large leak or from restriction. DTC will set after 2 consecutive failures during test.

This DTC will set if there is no misfire, fuel trim, injector control circuit, AIR, EGR, VSS, HO2S, TP, MAP, MAF, ECT or IAT DTCs are set. Battery voltage is 5-18 volts. BARO pressure greater than 75 kPa. Fuel level 15-85 percent of full capacity. ECT and IAT is 39-86°F (4-30°C). Start-up ECT and IAT within 16°F (9°C) of each other. Vacuum in EVAP system decays (leaks) at too fast a rate.