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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 5 (Engine Controls - Tests W/Codes - 2.3L) >> Circuit Tests >> DTC P0140 - Right Rear Heated Oxygen Sensor, Insufficient Activity Detected >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect all applicable harness connectors. Repair as needed. Turn ignition on. Access ECM harness connector. ECM is mounted in front of center console, under radio. Using voltmeter, backprobe applicable ECM harness connector. Measure voltage between ground and terminal No. 3D.
  2. Voltage should be 0-1.0 volt with engine idling at normal operating temperature. If voltage is within specification, go to step 6). If voltage is not within specification, go to next step.
  3. Turn ignition off. Disconnect right rear oxygen sensor harness connector. Using ohmmeter, backprobe ECM harness connector. Check continuity between terminal "B" on right rearb oxygen sensor harness connector and terminal No. 3AB on ECM connector. If continuity does not exist, repair Black/Yellow wire. If continuity exists, go to next step.
  4. Check continuity between terminal "A" on right rear oxygen sensor harness connector and terminal No. 3D on ECM connector. If continuity does not exist, repair White wire. If continuity exists, go to next step.
  5. Inspect fuel injectors, mass air flow sensor, engine coolant temperature sensor. See appropriate SYSTEM/COMPONENT TESTS - 2.3L article. Replace as needed. Inspect fuel pressure regulator. See appropriate BASIC TESTING - 2.3L article. Replace as needed. Inspect spark plugs and air intake system. Repair or replace as needed. If all items are okay, replace right rear heated oxygen sensor.
  6. Erase DTCs. See CLEARING CODES  in SELF-DIAGNOSTIC SYSTEM section. If DTC resets, replace ECM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.
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