P1647moderate severityPowertrain

Front Heated O2 Sensor Bank 2 Fault

on 2001 Volvo S80 2.9L I6 · AWD

What this code means

The ECM detected a fault in the front (upstream) heated oxygen sensor on Bank 2. The sensor signal or heater circuit is not providing reliable data for fuel trim control.

Symptoms

  • Check Engine Light
  • Poor fuel economy
  • Rough idle on Bank 2
  • Failed emissions test

Common causes

  • Faulty O2 sensor Bank 2
  • O2 sensor heater failure Bank 2
  • Exhaust leak at Bank 2 manifold
  • Wiring fault to sensor
  • Sensor connector corrosion

Diagnostic steps

  1. Test O2 sensor signal Bank 2
  2. Test heater circuit resistance
  3. Check for exhaust leaks at Bank 2
  4. Inspect wiring and connector
  5. Compare sensor data between banks

Repair notes

Replace the front heated O2 sensor on Bank 2.

Other Powertrain codes on this vehicle

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