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Home >> Jeep >> 1997 >> Wrangler Sahara, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 4.0L >> No Trouble Code Tests >> Test NTC-12A - Checking EVAP System

Test NTC-12A - Checking EVAP System

NOTE: For component location, see appropriate THEORY & OPERATION article.
  1. Start engine. Allow engine to reach operating temperature. Inspect throttle body-to-EVAP canister vacuum hoses for leaks or restrictions. Repair or replace hoses as necessary and perform TEST VER-2A. If hoses are okay, go to next step.
  2. Disconnect EVAP solenoid-to-EVAP canister hose. Using scan tool, select vapors test. Select No. 3. If EVAP solenoid does not allow vacuum to cycle through, replace EVAP solenoid and perform TEST VER-2A. If EVAP solenoid allows vacuum to cycle through, go to next step.
  3. Using scan tool, select No. 2. If EVAP solenoid allows vacuum to cycle through, replace EVAP solenoid and perform TEST VER-2A. If EVAP solenoid does not allow vacuum to cycle through, go to next step.
    CAUTION: DO NOT use more than 5 psi in following steps.
  4. Turn ignition off. Attempt to blow air through EVAP solenoid-to-canister hose. If air flows, EVAP solenoid and hoses are okay. Test passed. If air does not flow, go to next step.
  5. Disconnect EVAP solenoid-to-EVAP canister hose at EVAP canister. Attempt to blow air through EVAP solenoid-to-EVAP canister hose. If air flows, replace EVAP canister and perform TEST VER-2A. If air does not flow, repair or replace hose as necessary and perform TEST VER-2A.