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Home >> Mazda >> 1997 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P1170 - Front Oxygen Sensor Activity Not Detected >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Inspect all applicable harness connectors. Repair as needed. Turn ignition on. Access ECM harness connector. ECM is mounted to bulkhead, behind passenger seat. Using voltmeter, backprobe applicable ECM harness connector. Measure voltage between ground and terminal No. 3C.
  2. Voltage should be 0-1.0 volts with engine idling at normal operating temperature. If voltage is within specification, go to step 5). If voltage is not within specification, go to next step.
  3. Turn ignition off. Disconnect front oxygen sensor harness connector. Using ohmmeter, backprobe ECM harness connector. Check continuity between terminal "A" on oxygen sensor harness connector and terminal No. 3C on ECM connector. If continuity does not exist, repair Blue/Red wire. If continuity exists, go to next step.
  4. Inspect fuel injectors, mass air flow sensor, engine coolant temperature sensor. See appropriate SYSTEM/COMPONENT TESTS article in this section. Replace as needed. Inspect fuel pressure regulator. See appropriate BASIC TESTING article in this section. Replace as needed. Inspect spark plugs and air intake system. Repair or replace as needed. If all items are okay, replace front oxygen sensor.
  5. Erase DTC. See CLEARING CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC is present, replace ECM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.
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