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Home >> Chevrolet >> 1998 >> Venture Base, Van Cargo Extended >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0442 - EVAP Control System (Small Leak Detected) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
  2. Check if DTC P1665 or P1676 is also set. If any of DTC(s) is present, diagnose affected DTC(s). If DTCs are not present, go to next step.
  3. Turn ignition off. Remove fuel filler cap. Turn ignition on. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H2O, go to next step. If fuel tank pressure in not zero in. H2O, diagnose evaporative system.
  4. Replace fuel filler cap. Using scan tool, capture FAIL RECORD data for DTC P0440 and clear DTC. Command EVAP vent solenoid on. Connect EVAP Pressure/Purge Diagnostic Station (J 41413) to EVAP service port. Pressurize EVAP system using diagnostic station. Monitor pressure on EVAP pressure gauge on diagnostic station. If pressure is 5 in. H2O, go to next step. If pressure is not 5 in. H2O, go to step 6).
  5. Turn ignition on, with engine off. Using scan tool, command EVAP vent solenoid on. Using diagnostic station, pressurize EVAP system to 15 in. H2O and monitor pressure on EVAP pressure gauge on diagnostic station. Move rotary switch on diagnostic station to HOLD position. If EVAP pressure decreases to less than 10 in. H2O within 2 minutes, go to next step. If pressure does not decrease as specified, see DIAGNOSTIC AIDS.
  6. Disconnect fuel tank vapor line and EVAP purge line from EVAP canister. Block canister fitting for fuel tank pressure line. Connect a hand-held vacuum pump to canister fitting for EVAP purge line. Ensure that EVAP vent solenoid is still commanded on. Apply vacuum to EVAP canister. If vacuum can be maintained at 5 in. Hg, go to step 9). If vacuum cannot be maintained at 5 in. Hg, go to next step.
  7. Check for disconnected or damaged vent hose. Check for damaged EVAP canister. Repair as necessary. After repairs, go to step 11). If no problems were found, go to next step.
  8. Replace EVAP purge solenoid. After replacing EVAP solenoid, go to step 11).
  9. Check for faulty or missing fuel filler cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If problem is found, repair as necessary. After repairs, go to step 11). If no problems were found, go to next step.
  10. Using scan tool, command EVAP vent solenoid on. Continuously attempt to pressurize the EVAP system by leaving the EVAP diagnostic station control knob in the pressurized position. Using the Ultrasonic Leak Detector (J 41416), locate and repair leak in EVAP system. After repairs, go to next step.
  11. Turn ignition on. Using scan tool, command EVAP vent solenoid on. Using EVAP diagnostic station, pressurize EVAP system to 15 in. H2O. Move rotary switch in diagnostic station to HOLD position and observe EVAP pressure gauge. If EVAP pressure decreases to less than 10 in. Hg within 2 minutes, repeat step 3). If EVAP pressure does not decrease, system is okay.
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