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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 48 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0136, DTC P1137 Or DTC P1138 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed and Continuous Memory DTCs P0350-P0354 or DTCs P0300-P0306 are present, repair them first. For other DTCs, go to next step.

  2. Check For HO2S KOER

    If DTCs P1137 or P1138 are present during QUICK TEST, go to next step. If DTCs P1137 or P1138 are not present during QUICK TEST, fault that produced DTC P0136 is intermittent. See INTERMITTENT  under SYSTEM TESTS.

  3. Visual Inspection

    Inspect wiring harness for stretched, pinched or corroded wires. DTCs P0136 or P0156 with P1137 and/or P11138 may be caused by exhaust leaks between engine and end of catalyst. Inspect exhaust for holes and cracks. Check exhaust flanges for leaks. Check HO2S torque. If none of these conditions are present, go to next step. If any of these conditions are present, repair as necessary. Go to step  10 .

  4. Check HO2S Harness For Short To VPWR & Ground

    Disconnect scan tool from DLC. Disconnect PCM connector. Install breakout box, leaving PCM disconnected. Disconnect rear HO2S connector. Measure resistance between breakout box terminal No. 35 and terminal No. 71/97 (short to VPWR). Record reading. Measure resistance between breakout box terminal No. 35 and terminal No. 91 (short to SIG RTN circuit). Record reading. Measure resistance between breakout box terminal No. 35 and terminal No. 90 (short to VREF circuit). Record reading. Measure resistance between breakout box terminal No. 35 and terminal No. 103 (short to PWR GND circuit). Record reading. If each resistance value is more than 10,000 ohms, go to next step. If any resistance value is 10,000 ohms or less, repair short in appropriate wiring harness. See WIRING DIAGRAMS article. Go to step  10 .

  5. Check Resistance Of HO2S SIG & Ground Circuits For Open In Harness

    Measure resistance of HO2S SIG circuit between breakout box terminal No. 35 and HO2S harness connector (White/Black wire). See Fig 1 . Record reading. Measure resistance of HO2S SIG RTN circuit between breakout box terminal No. 91 and HO2S harness connector (Orange wire). Record reading. Measure resistance of HO2S VPWR circuit between breakout box terminal No. 71/97 and HO2S harness connector (Light Blue/Orange wire). Record reading. If each resistance reading is less than 5 ohms, go to next step. If any resistance reading is 5 ohms or more, repair open in appropriate circuit. See WIRING DIAGRAMS article. Go to step  10 .
    Fig 1: HO2S Harness Connector Circuit Identification
    G95E35968Courtesy of MAZDA MOTORS CORP.

  6. Check HO2S Circuit Voltage

    Remove breakout box. Reconnect PCM connector and rear HO2S. Connect scan tool to DLC. With KOEO, access O2S12 PID. Observe voltage. If voltage is more than 1.5 volts, go to step  9 . If voltage is 1.5 volts or less, go to next step.

  7. Check Resistance Of HO2S Ground Circuit In PCM

    Turn ignition off. Disconnect PCM connector. Install breakout box and connect PCM to breakout box. Leave vehicle harness disconnected from breakout box. Measure resistance between breakout box terminals No. 91 (SIG RTN circuit) and No. 103 (PWR GND circuit). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace faulty PCM. Go to step  10 .

  8. Apply 12 Volts To Suspect HO2S Circuit

    Remove breakout box. Connect PCM connector. Disconnect rear HO2S connector. Jumper VPWR circuit (Light Blue/Orange wire) to HO2S SIG circuit (White/Black wire) at HO2S vehicle harness connector. See Fig 1 . With KOEO, access O2S12 PID. Observe voltage. If voltage is more than 1.5 volts, replace faulty rear HO2S. Go to step  10 . If voltage is 1.5 volts or less, replace faulty PCM. Go to step  10 .

  9. Check For Over Voltage On HO2S Circuit In PCM

    Disconnect rear HO2S connector. With KOEO, measure voltage between SIG RTN circuit (Orange wire) at HO2S harness connector and battery negative terminal. See Fig 1 . Record reading. With KOEO, measure voltage between SIG circuit (Orange wire) at HO2S harness connector and battery negative terminal. Record reading. If either voltage reading is more than 1.5 volts, replace faulty PCM. Go to next step. If either voltage reading is 1.5 volts or less, replace faulty rear HO2S. Go to next step.

  10. Verify Trouble Shooting Of DTCs Completed

    Make sure all electrical connectors are reconnected. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If the same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTCs are present, test is complete.
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