Scania EMS DTC 43521 SCR – Nitrogen oxides (NOx) downstream of the catalytic converter

EMS Engine Management System · Scania

Code 43521 (decimal). Some diagnostic tools show it in hexadecimal as AA01.

In short

The measured level of nitrogen oxides (NOx) is higher than it should be.

Applies to: EMS S6

What does Scania EMS fault code 43521 mean?

What causes Scania DTC 43521?

How to fix Scania EMS fault code 43521?

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This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.