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Home >> Jeep >> 1999 >> Wrangler SE, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Self-Diagnostic Tests >> DTC P0442: EVAP Leak Monitor Small Leak Detected

DTC P0442: EVAP Leak Monitor Small Leak Detected

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION  . For circuit identification and wiring diagram, see WRANGLER wiring diagram in WIRING DIAGRAMS article.
NOTE: DTC P0442: EVAP LEAK MONITOR SMALL LEAK DETECTED is monitored immediately after a cold start, with ambient temperature 40 -90°F (4.4-32.2°C) and engine coolant temperature within 10°F of ambient temperature. DTC may be stored in Powertrain Control Module (PCM) when PCM senses a leak .04-.08" (.01-.02 mm) in Evaporative Emission (EVAP) system. Possible causes are: damaged EVAP hose, leaking EVAP system component, leaking Leak Detection Pump (LDP), loose fuel tank cap, defective secondary seal in fuel filler neck, defective connectors or defective wiring.
NOTE: EVAP purge solenoid may also be referred to as EVAP canister purge solenoid or duty cycle EVAP purge solenoid.
NOTE: Replacing PCM will not correct this problem.
  1. Turn ignition on, with engine off. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP COUNTER is displayed and displayed count is "0", go to step 3). If DTC SPECIFIC GOOD TRIP COUNTER is not displayed or displayed count is not "0", go to next step.
  2. At this time, DTC P0442: EVAP LEAK MONITOR SMALL LEAK DETECTED does not exist or is an intermittent problem. Using scan tool, read and record FREEZE FRAME data. Road test vehicle under conditions in FREEZE FRAME data, paying particular attention to fault setting conditions such as speed, temperature, load and MAP vacuum. Using scan tool, read DTCs. If DTC P0442: EVAP LEAK MONITOR SMALL LEAK DETECTED returns, go to next step. If DTC P0442: EVAP LEAK MONITOR SMALL LEAK DETECTED does not return, see INACTIVE DTC CONDITION  . Test is complete.
    CAUTION: When performing test procedures, keep lighted cigarettes, sparks, flames and other ignition sources away from test area. Ensure fuel tank is at least 1/2 full. Pressurizing fuel tank with less than 3 gallons of gasoline may result in an explosion caused by ignition of fumes. Wear safety glasses during test. If vehicle is not being tested on a hoist, ensure parking brake is applied and all wheels are blocked before starting test.
    NOTE: Miller EVAP System Testing Kit (6872A) and Supply Hose (6922) are required to perform EVAP system pressure self-test.
  3. Using EVAP system testing kit, supply hose and instructions printed on EVAP system testing kit cover, perform EVAP system pressure pump self-test. Turn ignition on, with engine off. Using scan tool, go to ENGINE SYSTEM TESTS and select LEAK DETECTION PUMP TEST. Read instructions on scan tool and then press ENTER. At LEAK DETECTION PUMP TEST, select #3 HOLD PSI. Using hand-held vacuum pump, apply 20 in. Hg to vacuum hose going to LDP. LDP is located at left rear corner of engine compartment, below LDP filter. LDP filter is next to EVAP canister. Remove fuel tank cap. Install one end of supply hose on fuel tank cap, and then install fuel tank cap on vehicle. Install other end of supply hose on EVAP system testing kit. Connect EVAP system testing kit positive lead to positive battery terminal. Connect EVAP system testing kit negative lead to negative battery terminal. Set EVAP system testing kit PRESSURE/HOLD valve to OPEN. Set VENT valve to CLOSED. While monitoring EVAP system testing kit pressure gauge, turn EVAP system testing kit pump timer on. When pressure gauge reads 14 in. H20, turn PRESSURE HOLD valve to CLOSED. Turn timer off. Note time and pressure. If pressure drops more than 6 in. H20 in 2 minutes, go to next step. If pressure drops 6 in. H20 or less in 2 minutes, go to step 5).
    NOTE: In addition to Miller EVAP System Testing Kit (6872A) and Supply Hose (6922), Ultrasonic Leak Detector (6904) is required to perform this step.
  4. Using EVAP system testing kit, supply hose and instructions printed on EVAP system testing kit cover, perform EVAP system pressure pump self-test. Turn ignition on, with engine off. Using scan tool, go to ENGINE SYSTEM TESTS and select LEAK DETECTION PUMP TEST. Read instructions on scan tool and then press ENTER. At LEAK DETECTION PUMP TEST, select #3 HOLD PSI. Using hand-held vacuum pump, apply 20 in. Hg to vacuum hose going to LDP. Remove fuel tank cap. Install one end of supply hose on fuel tank cap, and then install fuel tank cap on vehicle. Install other end of supply hose on EVAP system testing kit. Connect EVAP system testing kit positive lead to positive battery terminal. Connect EVAP system testing kit negative lead to negative battery terminal. Set EVAP system testing kit PRESSURE/HOLD valve to OPEN. Set VENT valve to OPEN. Turn EVAP system testing kit pump timer on. Move EVAP system kit pressure gauge away from vehicle. Using ultrasonic leak detector, check for leaks at fuel tank cap, rollover valve, EVAP canister, LDP and EVAP purge solenoid. Repair or replace leaking component(s) as necessary. Perform TEST VER-6A. If no leaks exist, replace LDP. Perform TEST VER-6A.
  5. At this time, conditions required to set DTC are not present. Turn ignition off. Visually inspect related connectors, hoses and wiring harness for damage. Repair connectors, hoses and wiring harness as necessary. Perform TEST VER-6A. If connectors, hoses and wiring harness are okay, test is complete.
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