Powertrain
Definition only
Lights the check engine lamp
P2D20: Reductant System Flow – Blocked
Standardized SAE J2012 code · P2Dxx codes
What does P2D20 mean?
The SCR module detects fully blocked flow in the reductant system. No reductant reaches the injector despite commanded dosing.
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 Reductant injector clogged
- Medium Frozen reductant in cold weather
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2D20 on the same make and model first.
P2D20 in the community
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