P2ADA code meaning
Reductant Tank Temperature Sensor B Circuit Range/Performance
Powertrain system Generic code P2Axx codes Check engine light
What P2ADA means
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.
P2ADA at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P2ADA
- Check engine light after a cold start
- DEF or SCR warning message
Common causes of P2ADA
- Most likelyDEF quality sensor with drifting temperature element
- PossibleReference temperature sensors reading wrong
- PossibleChafed engine harness disturbing the signals
- Less likelyController software needing an update
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant tank temperature sensor bReductant tank
What each part of P2ADA means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| DA | The exact fault in that area. |
What to do next
- Note P2ADA and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2ADA
What does P2ADA mean?
P2ADA means "Reductant Tank Temperature Sensor B Circuit Range/Performance". P2ADA checks whether the second DEF tank temperature reading is plausible. It is a generic code, so it means the same on every make.
Is it safe to drive with P2ADA?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2ADA fail an emissions test?
Yes, it can. P2ADA is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2ADA to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P2ADA clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.