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P1155moderate severityPowertrain

HO2S Lean Mean Bank 2 Sensor 1

on 2000 GMC Savana 4.3L V6 · RWD

What this code means

The upstream oxygen sensor on bank 2 reports a consistently lean average air-fuel mixture. This is a GM-specific code related to generic P0171 lean condition.

Symptoms

  • Check engine light on
  • Hesitation on acceleration
  • Poor fuel economy

Common causes

  • Vacuum or intake leak
  • Weak fuel delivery
  • Faulty O2 sensor
  • Dirty MAF sensor

Diagnostic steps

  1. Scan and record fuel trim data
  2. Check for intake and vacuum leaks
  3. Test fuel pressure
  4. Inspect MAF and O2 sensor

Other Powertrain codes on this vehicle

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