LEMON Manuals: Even more car manuals for everyone
Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 100 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0171, DTC P0172, DTC P0174 Or DTC P0175 >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check connection of PCV hose. Repair as necessary. If okay, go to next step.
  3. Check fuel injectors. See Figure. Injector volume should be 3.7-4.5 cu. in. (60-73 cm3 ) per 15 seconds. Difference between each injector should be .6 cu. in. (13 cm3 ) or less. If problem exists, repair as necessary. If problem does not exist, go to next step.
  4. Disconnect Mass Airflow (MAF) sensor connector. Measure resistance between connector terminals No. 4 and 5. See MASS AIRFLOW SENSOR RESISTANCE BETWEEN TERMINALS NO. 4 & 5 . Reconnect connector. Turn ignition on. Measure voltage between terminals No. 2 and 3 of MAF sensor. See Fig 1 and Fig 2 . If voltage fluctuates, go to next step. If voltage does not fluctuates, replace MAF meter.
    MASS AIRFLOW SENSOR RESISTANCE BETWEEN TERMINALS NO. 4 & 5

    Resistance Temperature
    13.6-18.4 k/Ohms -4°F (-20°C)
    2.21-2.69 k/Ohms 68°F (20°C)
    .49-.67 k/Ohms 140°F (60°C)
    Fig 1: Identifying Mass Airflow Sensor Connector Terminals No. 4 & 5
    G00239959Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 2: Identifying Mass Airflow Sensor Connector Terminals No. 2 & 3
    G00239960Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  5. Check Engine Coolant Temperature (ECT) sensor. See Fig 3. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - GS300, IS300, GS430, LS430 & SC430 article. If problem exists, replace sensor. If problem does not exist, go to next step.
    Fig 3: Checking Engine Coolant Temperature (ECT) Sensor
    G00239961Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  6. Check spark and ignition system. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Check fuel pressure. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm2 ) and remain at 21 psi (1.5 kg/cm2 ) for 5 minutes after engine has stopped. If fuel pressure is not within specification, replace fuel pump. If fuel pressure is within specification, go to next step.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Start engine and raise engine speed to 2500 RPM for about 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensor No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt to more than .6 volt. See Figure. If voltage is as specified, go to step  11. If voltage is not as specified, go to next step.
  10. Disconnect the H9, H10, H15 and H16 heated oxygen sensor connectors. Disconnect the E3, E4 and E5 ECM connectors. See Figure and Figure . Check the continuity between the wire harness side connectors. See HO2S/ECM CONTINUITY CHECK  table. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate heated oxygen sensor.
    HO2S/ECM CONTINUITY CHECK

    Terminals No. Specification
    OX (H9-3) - OXL 1 (E3-28) Continuity
    HT (H9-1) - HTL (E3-9) Continuity
    OX (H10-3) - OXR1 (E4-28) Continuity
    HT (H10-1 ) - HTR (E4-30) Continuity
    OX (H15-4) - OXL2 (E5-28) Continuity
    HT (H15-2) - HTL2 (E5-7) Continuity
    OX (H16-4) - OXR2 (E5-17) Continuity
    HT (H16-2) - HTR2 (E5-8) Continuity
    OX (H9-3) Or OXL1 (E3-28) - E1 (E3-7) No Continuity
    HT (H9-1) Or HTL (E3-9) - E1 (E3-7) No Continuity
    OX (H10-3) Or OXR1 (E4-28) - E1 (E3-7) No Continuity
    HT (H10-1) Or HTR (E4-30) - E1 (E3-7) No Continuity
    OX (H15-4) Or OXL2 (E5-28) - E1 (E3-7) No Continuity
    HT (H15-2) Or HTL2 (E5-7) - E1 (E3-7) No Continuity
    OX (H16-4) Or OXR2 (E5-17) - E1 (E3-7) No Continuity
    HT (H16-2) Or HTR2 (E5-8) - E1 (E3-7) No Continuity
  11. Perform confirmation test drive , then go to next step. See CONFIRMATION DRIVING PATTERN .
  12. Clear and recheck for DTCs. If DTCs P0171, P0172, P0174 or P0175 are displayed again, replace ECM. If DTCs P0171, P0172, P0174 or P0175 are not displayed, go to next step.
  13. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
scientia non olet · About LEMON Manuals