OBD code P20EE

The SCR system is not reducing NOx with the expected efficiency, usually related to AdBlue, the SCR catalyst or NOx sensors.

Estimated severity

High

Common symptoms

AdBlue or emissions warning
Check engine light on
Possible start countdown
Possible limp mode
Usually little change in engine performance at first

Likely causes

Incorrect or contaminated AdBlue
Faulty AdBlue injector or pump
Crystallization in the injector or line
Faulty upstream or downstream NOx sensor
Exhaust leak before the SCR catalyst
SCR catalyst aged or contaminated

Recommended checks

1. Check AdBlue level and quality before replacing expensive components.
2. Read NOx sensor values before and after the SCR catalyst.
3. Perform an AdBlue dosing or pressure test if supported.
4. Inspect the injector for crystallization and the exhaust for leaks.
5. Check related SCR module codes, not only the generic engine code.
6. Clear the code only after the SCR monitor can pass again.

What does code P20EE mean?

P20EE means the SCR emissions system is not reducing NOx as expected. On Euro 6 diesel vans, it may be caused by poor AdBlue quality, dosing failure, a blocked or crystallized injector, NOx sensor error, exhaust leak or SCR catalyst deterioration. This code can lead to power limits or a start countdown.

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