OBD-II code · Powertrain (generic, extended)
P2D20 Reductant System Flow – Blocked
The SCR module detects fully blocked flow in the reductant system. No reductant reaches the injector despite commanded dosing.
Is it safe to drive with P2D20?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyReductant injector clogged
- PossibleFrozen reductant in cold weather
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)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–6 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Reductant Lines, Reductant Injector, Reductant Pump, Scr Module
Related codes
- P2D1DReductant System Leak Detected – Small Leak
- P2D1EReductant System Leak Detected – Large Leak
- P2D1FReductant System Flow – Restricted
- P2D21Turbocharger Interstage Pressure Sensor A Circuit
- P2D22Turbocharger Interstage Pressure Sensor A Circuit Range/Performance
- P2D23Turbocharger Interstage Pressure Sensor A Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.