Circuit Description

Evaporative leak detection strategy is based on applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system. Whenever a sufficient vacuum level cannot be achieved, a large leak or faulty EVAP purge solenoid is indicated.

Conditions for setting this DTC are:

• DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134 and P1133 not set.
• BARO greater than 75 kPa.
• IAT and ECT are 41-84°F (5-29°C) at engine start-up.
• IAT is not greater than 2°F (1°C), greater than ECT at start-up.
• TP sensor is 7-35 percent.
• ECT is not greater than 12°F (7°C), greater than IAT at start-up.
• Fuel tank level is 26-74 percent.
• EVAP solenoid is at 50 percent PWM within 50 seconds of engine start-up.
• EVAP system is unable to achieve or maintain vacuum during diagnostic test. Amount of vacuum decay will vary with fuel level.