How to replace DEF Doser Valve on VOLVO & MACK trucks - MOTIV8 Engineering

Detailed instructions how to Replace DEF Doser Valve on VOLVO & MACK Trucks

  • Please read this manual carefully before installation.
  • Please also refer to the Mack / Volvo Service Manual in conjunction with this manual.
  • After the installation has been completed, please keep this manual for future reference.
  • If the installation was done in a shop, please make sure to give this manual to the owner.

Kit Contents

  • DEF Dosing Unit / Urea Injection

Required tools

  • Mack / Volvo workshop service manual
  • Mechanic’s tool kit


  • This product was designed specifically for the application specified. If an attempt is made to use this product on another car other than specified, you will risk damaging this part and components related to it.
  • Please have regular maintenance checks to ensure the item remains securely fitted.
  • Do not use any excessive force when using this product as you risk damaging the product or other parts.
  • This product must be installed with the appropriate tools and equipment to prevent any electrical failures, injuries, or bodily harm.


Preparing for replacement:

  1. Park your vehicle.
  2. Engage the parking brake to ensure your vehicle will not move. Shut off the engine and ignition, and remove the key from the ignition switch.

! Wait at least two minutes before disconnecting hoses to let the SCR system automatically empty them.


  1. Remove all body elements according to the vehicle manual to get access to the DEF Dosing Unit.
  2. ATTENTION!: Clean the DEF tank and hoses before disconnecting them to avoid damages caused by debris.
  3. Disconnect the electrical connector.
  4. Unplug the DEF line from the DEF Dosing Unit.
  5. Clamp up Dosing Unit coolant hoses to avoid coolant drain off.
  6. Unplug coolant hoses. ATTENTION! Some engine coolant will drain off. Prepare a designated coolant container to hold the coolant while you continue the repair.
  7. Unscrew the bolts and remove the old DEF Dosing Unit.
  8. Clean up the Dosing Unit mounting surface.
  9. Replace gasket if needed.
  10. Install the new Module.
  11. Tighten the fixing bolts with torque 10+- 1.5 Hm.
  12. Remove the caps from the new Unit and connect hoses.
  13. Unclamp coolant hoses.
  14. Plug the electrical connector back in.
  15. Install removed body elements in reverse order.
  16. Refill the radiator up to the recommended coolant level if needed.
  17. Start the engine.
  18. Check for any leakage.
  19. Calibrate the Dosing Module with diagnostic equipment if needed.

If you do not feel confident doing the job yourself, have a certified technician perform the replacement.

You can purchase a new DEF Doser Valve on VOLVO & MACK Trucks by following the link: Volvo DEF Doser Valve for Volvo & Mack