P1152moderate severityPowertrain

Lack of HO2S Switch — Sensor Indicates Rich (Bank 2)

on 2019 Ford Explorer 3.5L V6 · FWD

What this code means

The upstream heated oxygen sensor on Bank 2 is not switching and indicates a persistent rich condition. The sensor is stuck indicating a rich mixture on Bank 2.

Symptoms

  • Check Engine Light
  • Rich exhaust smell
  • Black exhaust smoke
  • Poor fuel economy
  • Rough idle

Common causes

  • Leaking fuel injector Bank 2
  • High fuel pressure
  • Faulty O2 sensor stuck rich
  • EVAP purge issue
  • Coolant entering combustion chamber Bank 2

Diagnostic steps

  1. Monitor O2 sensor Bank 2 on scan tool
  2. Check fuel pressure
  3. Inspect spark plugs Bank 2 for fouling
  4. Check for leaking injectors

Repair notes

Replace O2 sensor if stuck. Check fuel pressure regulator. Inspect injectors.

Other Powertrain codes on this vehicle

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