P2ADA: Reductant Tank Temperature Sensor B Circuit Range/Performance
What to do
AdBlue faults run on a legally mandated countdown — reduced power and eventually no restart, with the remaining miles shown on the dashboard. The car is fine to drive now and will not stay that way, so do not defer it.
What this code means
The circuit for the second reductant tank temperature sensor is faulty.
This measures the temperature of the AdBlue in the tank, where P2ACC measures it in the line, and the pair exist because freezing starts in different places.
AdBlue freezes at about −11 °C, which is an ordinary winter night. The tank is the large thermal mass — slow to freeze and slow to thaw — while the lines are thin and freeze first. So the tank sensor decides when the tank heater runs and when there is usable fluid at all, and the line sensor decides whether dosing can resume.
Getting that wrong in either direction is expensive. Heating a tank that is not frozen wastes energy and ages the fluid, which degrades above about 30 °C and turns to ammonia. Failing to heat one that is frozen leaves the car unable to dose, which starts the emissions countdown.
A second tank sensor implies a large tank — a commercial vehicle, or a passenger car with a long service interval — where a single reading would not represent the whole volume.
Note the allocation. The base
Circuitcode for this family is P2ADE, after its four variants at P2ADA–P2ADD rather than before them. That is the same out-of-order pattern the corpus records at P0EBB and P0EC0, and it is not inferable — check the address, do not derive it.
Present and plausible but not agreeing with what the rest of the system reports — drift rather than failure.
Likely causes
Start here
- Faulty reductant temperature sensor · specialist
- Corroded or loose connector · specialist
- Open circuit in sensor wiring · specialist
Less common
- Damaged wiring harness · specialist
- Failed sensor reference voltage supply · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P2ADA.