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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 41 (Engine Controls - Self-Diagnostics - Quest) >> Diagnostic Tests >> DTC P0440: EVAP Control System (Small Leak - Negative Pressure) Or DTC P1440: EVAP Control System (Small Leak - Positive Pressure) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure fuel filler cap is original equipment. Attempt to turn fuel cap clockwise. If fuel cap was tightened properly, go to next step. If fuel cap was not tightened properly, clean fuel cap and filler neck. Reinstall cap and retest system.
  2. While removing fuel cap, listen for air escaping from fuel tank. If air escaped from fuel tank, go to step  4. If air did not escape from fuel tank, go to next step.
  3. Using a suitable hand vacuum/pressure pump with fuel cap adapter, apply pressure and vacuum to fuel cap. Fuel cap vacuum relief valve should open when pressure reaches 2.22-2.90 psi (15.3-20.0 kPa) and when vacuum reaches -.50 to -.87 psi (-3.4 to -6.0 kPa). If operation is as specified, go to next step. If operation is not as specified, replace fuel cap and retest system.
    CAUTION: Do not use compressed air. Do not apply more than .6 psi (4.12 kPa) of pressure to EVAP system.
  4. Turn ignition off. Disconnect EVAP-CVCV harness connector. See Fig 1. Disconnect vacuum cut valve by-pass valve harness connector. See Fig 2. Connect a pressure pump to EVAP service port. See Fig 3. Using fused jumper wires, apply battery voltage between EVAP-CVCV terminals. EVAP-CVCV should close. Using fused jumper wires, apply battery voltage between vacuum cut valve by-pass valve terminals. Vacuum cut valve by-pass valve should open. Apply .2-.4 psi (1.3-2.7 kPa) of pressure to EVAP system. Check EVAP system for leaks. See VACUUM DIAGRAMS article. If any leaks are found, repair as necessary and retest system. If no leaks are found, go to next step.
    5. CAUTION: Do not disassemble water separator.
  5. Reconnect all components. Remove water separator located on charcoal canister. Inspect water separator for cracks or blockage. With water separator port "A" plugged, blow air into port "B". See Fig 4. Air should flow out of port "C". With port "C" plugged, blow air into port "B". Air should flow out of port "A". If operation is as specified, go to next step. If operation is not as specified, replace water separator and retest system.
  6. Reconnect all components. Check EVAP-CVCV, "O" ring and circuit. See DTC CONFIRMATION TEST  under DTC P0446: EVAP CANISTER VENT CONTROL VALVE. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  7. Remove EVAP canister with EVAP-CVCV attached. Turn EVAP canister so EVAP-CVCV is pointing down. If water drains out, go to next step. If water does not drain out, go to step  9.
  8. Weigh EVAP canister with EVAP-CVCV attached. If weight is less than 4 lbs. (1.8 kg), go to next step. If weight is 4 lbs. (1.8 kg) or more, check EVAP canister for damage. Also, check hose between EVAP canister and water separator for clogging or poor connection. Repair hose or replace EVAP canister as necessary and retest system.
  9. Install components and reconnect all harness connectors. Start engine and warm to normal operating temperature. Turn ignition off. Disconnect EVAP-CPVCV vacuum hose at EVAP service port. Start engine and let it idle for at least 80 seconds. Increase engine speed to 2000 RPM while checking for vacuum at disconnected vacuum hose. If vacuum exists, go to step  14. If vacuum does not exist, go to next step.
  10. Turn ignition off. Check for disconnected or damaged vacuum hoses between EVAP service port and EVAP-CPVCV, and between EVAP-CPVCV and intake manifold. See VACUUM DIAGRAMS article. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  11. Disconnect vacuum hoses from EVAP-CPVCV. See Fig 5. Disconnect EVAP-CPVCV harness connector. Apply air pressure to port "A" at EVAP-CPVCV. See Fig 6. Air should not flow from port "B". Using fused jumper wires, apply battery voltage between EVAP-CPVCV terminals. Air should now flow from port "B". If EVAP-CPVCV does not operate as specified or operation takes more than one second, replace EVAP-CPVCV and retest system. If EVAP-CPVCV operates as specified, go to next step.
    12. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  12. Remove AP sensor with its harness connector connected. See Figure. Turn ignition on. Measure voltage between ground and AP sensor signal circuit at ECM terminal No. 45 (Pink wire) by backprobing. Voltage should be 3.2-4.8 volts. Using a hand vacuum pump, apply 7.87 in. Hg of vacuum to AP sensor. Voltage should be 1.0-1.4 volts less than voltage measured with no vacuum applied. If voltage is as specified, go to next step. If voltage is not as specified, replace AP sensor and retest system.
  13. Remove MAP/BARO solenoid. See Figure. Using fused jumper wires, apply battery voltage between MAP/BARO solenoid terminals. See Figure. Ensure air flows between ports "A" and "B" and does not flow between ports "A" and "C". Remove jumper wires. Ensure air does not flow between ports "A" and "B" and flows between ports "A" and "C". If air does not flow as specified or operation takes more than one second, replace MAP/BARO solenoid and retest system. If air flows is as specified, go to next step.
  14. Remove fuel pump assembly from fuel tank. Measure resistance between fuel pump assembly connector terminals No. 1 and 4 (component side). See Figure. Resistance should be 2300-2700 ohms at 68°F (20°C) and 790-900 ohms at 122°F (50°C). Resistance should decrease as temperature increases. See Figure. If resistance is not as specified, replace FTT sensor and retest system. If resistance is as specified, go to next step.
    CAUTION: Do not apply more than 5.91 in. Hg of vacuum to EVAP-CSPS. Replace EVAP-CSPS if it has been dropped from a height of more than 20" (.5 m) onto a hard surface such as concrete.
    15. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  15. Remove EVAP-CSPS with its harness connector connected. See Fig 7. Turn ignition on. Using a vacuum pump, apply 2.76 in. Hg of vacuum to EVAP-CSPS vacuum port. Measure voltage between ground and EVAP-CSPS signal circuit at ECM terminal No. 62 (Red wire) by backprobing. Voltage should be .4-.6 volt. Disconnect vacuum pump. Voltage should be 3.0-3.6 volts. If voltage is as specified, go to next step. If voltage is not as specified, replace EVAP-CSPS and retest system.
  16. Check purge line for cracks or improper connection. See VACUUM DIAGRAMS article. Repair as necessary and retest system. If purge line is okay, clean purge line with compressed air. Go to next step.
  17. Remove fuel pump assembly from fuel tank. Measure resistance between fuel pump assembly connector terminals No. 5 and 6 (component side), with float rod in specified positions. See FUEL LEVEL SENSOR RESISTANCE  table. See Figure. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel level sensor and retest system.
  18. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
FUEL LEVEL SENSOR RESISTANCE

Float Position Ohms
Full (1) 160
1/2 84
Empty (1) 15
(1) When float rod is in contact with stop.
Fig 1: Locating EVAP Canister Vent Control Valve
G99C50460Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating Vacuum Cut Valve & Vacuum Cut Valve By-Pass Valve
G99I50441Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 3: Locating EVAP Service Port
G00042090Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 4: Testing Water Separator
G99H54806Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 5: Locating EVAP Canister Purge Volume Control Valve
G99I50458Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 6: Testing EVAP Canister Purge Volume Control Valve & Vacuum Cut Valve By-Pass Valve
G98D01303Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 7: Locating EVAP Control System Pressure Sensor
G99E50462Courtesy of NISSAN MOTOR CO., U.S.A.
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