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1998 TOYOTA 4RUNNER
3.4L V6•4WD•AUTOMATIC•gas
4 active safety recalls on this vehicle — view recalls
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Repairs0Labor515Torque3482Fluid10DTC1663Battery1Maintenance0Recalls4
P0146low severityPowertrain

O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)

on 1998 Toyota 4Runner 3.4L V6 · 4WD

What this code means

The third oxygen sensor on bank 1 shows no activity. The signal is flat and not switching as expected.

Symptoms

  • Check engine light on
  • Failed emissions test
  • No downstream O2 activity

Common causes

  • Faulty oxygen sensor
  • Open circuit in wiring
  • Blown fuse or heater fault
  • Corroded connector

Diagnostic steps

  1. Monitor O2 sensor signal for activity
  2. Check sensor heater circuit and fuse
  3. Inspect wiring and connector
  4. Replace sensor if inactive
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