P2ADAReductant Tank Temperature Sensor B Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Check engine light after a cold start
- DEF or SCR warning message
- Likely causes
- LikelyDEF quality sensor with drifting temperature element
- PossibleReference temperature sensors reading wrong
- PossibleChafed engine harness disturbing the signals
- RareController software needing an update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €150 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.