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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 125 (Engine Control System Self Diagnostics (2UZ-FE)) >> Diagnostic Tests >> DTC P0031, DTC P0032, DTC P0037, DTC P0038, DTC P0051, DTC P0052, DTC P0057 & DTC P0058 >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Disconnect HO2S 4-pin connector. See Fig 1. Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See HO2S HEATER RESISTANCE SPECIFICATIONS . If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See HEATED OXYGEN SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
    HO2S HEATER RESISTANCE SPECIFICATIONS

    Terminals No. Resistance in Ohms @ 68°F (20°C)
    1 (HT) & 2 (B+) 11-16
    1 (HT) & 4 (E1) No Continuity
  2. Remove EFI relay from engine room relay box. Test relay. See EFI RELAY under MODULES, MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
  3. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Turn ignition on. Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) (Brown wire) and ECM 35-pin connector E5 terminals No. 4 (+) (Light/Green wire), No. 5 (+) (Green/Yellow wire), No. 33 (+) (Black/Blue wire) and No. 25 (+) ( Pink wire). See Figure. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
    NOTE:
    • ECM 35-pin connector E5 terminal No. 4 (HT1A) is for HO2S (Bank 1 Sensor 1).
    • ECM 35-pin connector E5 terminal No. 5 (HT1B) is for HO2S (Bank 1 Sensor 2).
    • ECM 35-pin connector E5 terminal No. 33 (HT2A) is for HO2S (Bank 2 Sensor 1).
    • ECM 35-pin connector E5 terminal No. 25 (HT2B) is for HO2S (Bank 2 Sensor 2).
  4. Turn ignition off. Disconnect ECM 35-pin connector E5 and suspect HO2S 4-pin connector(s). Check continuity between appropriate ECM 35-pin connector terminal and appropriate HO2S connector terminal No. 1. There should be continuity. Then, check continuity between ground and appropriate HO2S connector terminal No. 1. There should be no continuity. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. Then go to next step.
  5. Check EFI fuse No. 2 located in engine room fuse/relay box. Replace as necessary. Disconnect EFI relay from engine room fuse/relay box. Check continuity between EFI main relay socket terminal No. 3 and suspect HO2S 4-pin connector terminal No. 2 (B+). Continuity should exist. Then, check continuity between ground and EFI main relay socket terminal No. 3. Continuity should not exist. If continuity is as specified, replace ECM. If continuity is not as specified, repair open or short circuit in wire or connector as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.
Fig 1: Identifying EFI Relay & HO2S Connectors & Terminals
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