Scania ZF DTC 4521 Proportional valve, retarder (Y1)

ZF ZF gearbox · Scania

Code 4521 (decimal). Some diagnostic tools show it in hexadecimal as 11A9.

In short

Incorrect signal from the retarder proportional valve.

Applies to: ZF1

What does Scania ZF fault code 4521 mean?

What causes Scania DTC 4521?

How to fix Scania ZF fault code 4521?

Read the full explanation with Premium

Causes, system reaction, symptoms and step-by-step repair instructions for every fault code are available to Premium members.

  • Full explanations of every code and brand
  • Causes, symptoms and repair steps
  • New brands and codes included
Get Premium – 7,50 € / month I already have an account

Yearly plan: pay 10 months, get 12. Cancel at any time.

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

Code 4521 in other Scania systems