Powertrain, generic (extended)

P2AD0 Reductant Temperature Sensor B Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2AD0 stands for short interruptions or jumps in the signal of reductant temperature sensor B. The current title reads circuit intermittent only, without erratic. No manufacturer publishes this test. The closest documented logic is GM's tank sensor check P205E in its 2025 DEF controller, which counts a failure when the value moves more than 4 °C within a ten-sample window and needs three such failures out of nine; sensor A has the corresponding code P2046. Because DEF crystallises when it leaks, a slightly damp connector can produce exactly these spikes; vibration loosening a terminal is the other classic cause. Steady faults are reported as P2ACE or P2ACF instead. Clean and dry the connector, check terminal grip and repeat a wiggle test with live data running.

Likely causes

Moisture or DEF residue in the sensor B connector
Terminal loosened by vibration
Wire breaking intermittently inside the insulation

Symptoms

  • Check engine light that appears sporadically
  • Jumping DEF temperature in live data

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant temperature sensor bwiring harness

Related codes

P2ACCP2ACDP2ACEP2ACFP2046

References: gsi.ext.gm.com, law.cornell.edu.