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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0135, DTC P0141, DTC P0155 Or DTC P0161 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda Tribute. 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 KOEO DTC P0135, P0141, P0155 and P0161 were not present, fault may be intermittent. Refer to INTERMITTENT  testing under SYSTEM TESTS. If same DTCs were present, go to next step.
  2. Visual Inspection -  Visually inspect suspect HO2S circuit for exposed wiring, contamination, corrosion and proper assembly. If no problems were found during visual inspection, go to next step. If any problems were found during visual inspection, repair as necessary. After repair, go to step  8.
  3. Check For VPWR At Vehicle Harness Connector -  If DTCs P0135 and P0155, P0141 or P0161 are displayed, both heater circuits will require testing. DTCs displayed separately are tested individually. Disconnect appropriate HO2S 4-pin harness connector(s). Turn ignition on, engine off. Measure voltage between HO2S 4-pin harness connector(s) VPWR terminal (Light Blue/Orange wire) and SIG RTN terminal (Orange wire). If voltage reading is more than 10.5 volts, go to next step. If voltage reading is 10.5 volts or less, check No. 5 FUEL PUMP fuse (15-amp) in engine compartment fuse/relay box. If fuse is okay, repair open circuit in Light Blue/Orange wire between No. 5 FUEL PUMP fuse (15-amp) and suspect HO2S 4-pin harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  8.
  4. Check HO2S Heater Resistance -  Disconnect suspect HO2S 4-pin harness connector. Measure resistance of HO2S HTR GND at component connector. For DTC P0135 (Red/White wire), P0141 (White/Black wire), P0155 (Yellow/Light Blue wire) or P0161 (Tan/Yellow wire). See Figure and Figure . If resistance reading is 3-30 ohms, go to next step. If resistance reading is not as specified, replace suspect HO2S. After repair, go to step  8.
  5. Check For HTR GND & VPWR Shorted To HO2S Case -  Measure resistance between HO2S HTR GND terminal at HO2S component connector and HO2S case. Measure resistance between HO2S HTR GND terminal and SIG RTN terminal (Orange wire) at HO2S component connector. Measure resistance between HO2S VPWR terminal (Light Blue/Orange wire) at HO2S component connector and HO2S case. If resistance readings are more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, replace suspect HO2S. After repair, go to step  8.
  6. Check For Shorts To Other Grounds & VPWR In HO2S HTR GND Harness Circuits -  Disconnect scan tool from DLC. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Use following list to measure resistance between appropriate breakout box terminals:
    • For DTC P0135, terminal No. 93 and terminals No. 71, 91 and 103.
    • For DTC P0141, terminal No. 100 and terminals No. 71, 91 and 103.
    • For DTC P0155, terminal No. 94 and terminals No. 71, 91 and 103.
    • For DTC P0161, terminal No. 96 and terminals No. 71, 91 and 103.

    If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, repair short circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  8.

  7. Check For Open HO2S HTR GND Harness Circuit -  Use following list to measure resistance between appropriate breakout box (HTR GND) terminal and HO2S 4-pin harness connector HTR GND terminal:
    • For DTC P0135, breakout box terminal No. 93.
    • For DTC P0141, breakout box terminal No. 95 (3.0L) or No. 100 (2.0L).
    • For DTC P0155, breakout box terminal No. 94.
    • For DTC P0161, breakout box terminal No. 96.
    If resistance reading is less than 4 ohms, open, shorted or excessive resistance in HTR circuit in PCM. Replace PCM. After repair, go to next step. If resistance reading is 4 ohms or more, repair open or excessive resistance in HTR GND circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  8. Verify Trouble Shooting Of DTCs Completed -  Reconnect all disconnected connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is not present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, procedure is complete.
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