Powertrain, generic (extended)

P2ADA Reductant Tank Temperature Sensor B Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2ADA checks whether the second DEF tank temperature reading is plausible. GM documents it twice. In its 2017–2018 diesel tables (and again in 25OBDG06C) it is the DEF quality sensor temperature offset: after more than 28,800 s off, the quality sensor's thermistor may differ from the average of the exhaust temperature sensors by no more than 35 °C; 40 of 50 samples failing set a Type A code. The 2025 DEF controller compares, at key on after a soak of over 8 h, the tank sensor B value with the secondary device temperature and fails beyond 21 °C (3 s out of 6, Type A). GM bulletin 21-NA-149 lists P2ADA among the codes from engine harness chafing on 2021 3.0L LM2 trucks. Circuit faults are P2ADB to P2ADE.

Likely causes

DEF quality sensor with drifting temperature element
Reference temperature sensors reading wrong
Chafed engine harness disturbing the signals
Controller software needing an update

Symptoms

  • Check engine light after a cold start
  • DEF or SCR warning message

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–1,800
Time0.5–4 h

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

Parts involved

reductant tank temperature sensor breductant tank

Related codes

P2ADBP2ADCP2ADDP2ADEP205B

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.