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Home >> Mazda >> 1997 >> Protege DX, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 1.5L >> Circuit Tests >> DTC P1170 - Front Oxygen Sensor, Activity Not Detected >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

  1. Inspect all applicable harness connectors. Repair as needed. Turn ignition on. Access PCM harness connector. PCM is mounted in front of center console, below radio. Using voltmeter, backprobe applicable PCM harness connector. Measure voltage between ground and terminal No. 3C.
  2. Voltage should be .5-1.0 volts during acceleration and 0-.5 volts during deceleration. 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 PCM harness connector. Check continuity between terminal "A" on front oxygen sensor harness connector and terminal No. 3C on PCM connector. If continuity does not exist, repair White wire. If continuity exists, go to next step.
  4. Inspect fuel injectors, mass air flow sensor, engine coolant temperature sensor. See the SYSTEM/COMPONENT TESTS - 1.5L article in this section. Replace as needed. Inspect fuel pressure regulator. See the BASIC TESTING - 1.5L 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  . If DTC is present, replace PCM. If DTC is not present, intermittent poor harness connection may have caused DTC to originally set.
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