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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda MPV and 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
  1. Record freeze frame data. Check for related service bulletins and on-line information. Repair as necessary and go to next step.
  2. Inspect Poor Connection Of HO2S (Right Front) Connector -  Turn ignition off. Disconnect right front HO2S 4-pin harness connector. Check for damaged, loose or corroded terminals. If problem is not present, go to next step. If problem is present, repair as necessary. After repair, go to step  8.
  3. Inspect HO2S Heater (Right Front) -  Measure resistance between right front HO2S terminals "C" and "D". See Fig 2. If resistance is 5.0-6.8 ohms, go to next step. If resistance is not 5.0-6.8 ohms, replace right front HO2S. After repair, go to step  8.
  4. Inspect Power Circuit Of HO2S Heater (Right Front) For Open Circuit -  Turn ignition on, engine off. Measure voltage in Black/White wire between ground and right front HO2S 4-pin harness connector terminal "C". If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/White wire between right front HO2S 4-pin harness connector terminal "C" and ignition switch. See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. After repair, go to step  8.
  5. Inspect Poor Connection Of PCM Connector -  Turn ignition off. Disconnect PCM 104-pin harness connector. Check for damaged, loose or corroded terminals. If problem is not present, go to next step. If problem is present, repair as necessary. After repair, go to step  8.
  6. Inspect Control Circuit Of HO2S Heater (Right Front) For Short To Ground -  Check continuity in Yellow wire between ground and right front HO2S 4-pin harness connector terminal "D". If continuity is not present, go to next step. If continuity is present, repair short to ground in Yellow wire between right front HO2S 4-pin harness connector terminal "D" and PCM 104-pin harness connector terminal No. 93. See Fig 3. After repair, go to step  8.
  7. Inspect Control Circuit Of HO2S Heater (Right Front) For Open Circuit -  Connect 104-pin Breakout Box (49-UN01-130) to PCM harness connector only. See Fig 1. Check continuity between right front HO2S 4-pin harness connector terminal "D" (Yellow wire) and breakout box terminal No. 93. If continuity is present, go to next step. If continuity is not present, repair open on Yellow wire between right front HO2S 4-pin harness connector terminal "D" and PCM 104-pin harness connector terminal No. 93. After repair, go to next step.
  8. Verify Trouble Shooting Of DTC P0031 Completed -  Reconnect all connectors. Turn ignition on, engine off. Using scan tool, clear DTC from memory. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0031 is not present, go to next step. If DTC P0031 is present, replace PCM. After repair, go to next step.
  9. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
Fig 1: Identifying 104-Pin Break Out Box
G00127421Courtesy of MAZDA MOTORS CORP.
Fig 2: Identifying Front HO2S 4-Pin Harness Connector Terminals
G00143777Courtesy of MAZDA MOTORS CORP.
Fig 3: Identifying PCM 104-Pin Harness Connector Terminals
G96F31315Courtesy of FORD MOTOR CO.
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