Powertrain
Definition only
Lights the check engine lamp
P2D1D: Reductant System Leak Detected – Small Leak
Standardized SAE J2012 code · P2Dxx codes
What does P2D1D mean?
The SCR module detects a small leak in the reductant system based on pressure decay rate after dosing pause. Slow loss of DEF/AdBlue.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Common causes
- High Fitting or connection loose
- Medium Seal aged at injector or pump
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2D1D on the same make and model first.
P2D1D in the community
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