P2D20
Reductant System Flow – Blocked
The SCR module detects fully blocked flow in the reductant system. No reductant reaches the injector despite commanded dosing.
The SCR module detects fully blocked flow in the reductant system. No reductant reaches the injector despite commanded dosing.
Common causes
- high
Reductant injector clogged
One of the most commonly reported causes for this code — check this first.
Typical part cost: $170-1650
- medium
Frozen reductant in cold weather
A plausible cause — test and verify before replacing parts.
Typical part cost: $170-1650
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for P2D20.
Unlock causesFree forever · No credit card
First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
Get the full step-by-step diagnosis
Create a free Wrenchify account to unlock the rest for P2D20.
Unlock diagnosisFree forever · No credit card
Related codes
See related trouble codes
Create a free Wrenchify account to unlock the rest for P2D20.
Unlock related codesFree forever · No credit card
Frequently asked questions
What does P2D20 mean?
P2D20 means "Reductant System Flow – Blocked". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P2D20?
reductant injector clogged; frozen reductant in cold weather — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.
Get the full P2D20 diagnosis for your vehicle
Year, make, model + step-by-step repair help — free plan included.