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P2BAA Powertrain

NOx Sensor Range/Performance (Bank 1, Sensor 1)

The upstream NOx sensor on bank 1 returns values that are not plausible for the current operating point. NOx sensors are slow to warm up, sensitive to soot and water, and are a frequent failure on diesel SCR systems.

Affected components

  • Nox sensor upstream
  • Nox sensor wiring

Common causes

  • High likelihood: NOx sensor element failed
  • Medium likelihood: Sensor contaminated with soot or condensate
  • Low likelihood: Sensor element aged beyond calibration window

Possible symptoms

  • Check engine light or NOx warning on
  • AdBlue/DEF level or quality warning
  • Possible no-start countdown after ignore period
  • Failed emissions inspection (NOx)

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions
  • A drive cycle may be required after repair

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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