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P2D5A

Reductant Level Sensor A/B Correlation

The signals of the reductant level sensors A and B do not correlate within the calibrated tolerance. One sensor drifts or installation offset between channels.

  • Check engine light: Yes
  • Emissions related: No
  • Repair difficulty: easy

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)

Common causes

Ordered by how often each turns out to be the cause.

  • One sensor characteristic driftedCommon
  • Harness incorrectly swapped between channelsPossible

Parts involved

  • Reductant Level Sensor A
  • Reductant Level Sensor B
  • SCR Module

P2D5A is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.