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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 27 (Engine Controls - Self-Diagnostics - 2.5L) >> Diagnostic Tests >> DTC P0161: Left Rear Ho2S Heater Circuit Malfunction >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs during KOEO and KOER self-test. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0161 is present, go to next step. If DTC P0161 is not present, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
  2. Turn ignition off. Disconnect left rear HO2S connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between left rear HO2S connector (component side) terminals "C" (Red/Black wire) and "D" (Violet/Red wire). Resistance should be approximately 6 ohms. If resistance is okay, go to next step. If resistance is not okay, replace left rear HO2S. After repair, go to step  8 .
  3. Turn ignition on with engine off. Using DVOM, check voltage between left rear HO2S connector (harness side) terminal "C" (Red/Black wire) and ground. Voltage should be B+. If voltage is okay, go to next step. If voltage is not okay, repair open circuit. See WIRING DIAGRAMS article. After repair, go to step  8 .
  4. Using DVOM, check voltage between left rear HO2S connector (harness side) terminal "D" (Violet/Red wire) and ground. If B+ voltage is not present, go to next step. If B+ voltage is present, repair short to power. See WIRING DIAGRAMS article. After repair, go to step  8 .
  5. Turn ignition off. Using DVOM, check continuity between left rear HO2S connector (harness side) terminal "D" (Violet/Red wire) and ground. If continuity is not present, go to next step. If continuity is present, repair or replace wiring harness as necessary. See WIRING DIAGRAMS article. After repair, go to step  8 .
  6. Disconnect PCM connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. After repair, go to step  8 . If connector is okay, go to next step.
  7. Turn ignition switch off. Connect 104-pin Breakout Box (49-UN01-130) to PCM 104-pin harness connector only. Leave PCM disconnected. Using DVOM, check continuity between left rear HO2S connector (harness side) terminal "D" (Violet/Red wire) and breakout box terminal No. 96. If continuity is present, go to next step. If continuity is not present, repair or replace wiring harness as necessary. See WIRING DIAGRAMS article. After repair, go to next step.
  8. Reconnect all connections. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Perform KOEO and KOER self-test. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0161 is present, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If DTC P0161 is not present, go to next step.
  9. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
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