The D10 engine was in November 2003 replaced by the D9 engine in A25D and A30D. The New D9 engine is a 9,4 litre engine (to be compared with 9,6 litre on the D10) derived from the same cutting edge technology as the well-proven D12 used in A35D and A40D. The D9 engine met US (EPA) step 2, California (CARB) step 2 and Europe (EU) step 2. With this new engine the products were prepared for coming emission standards and requirements for Tier 3.
In order to meet the Tier 3 / Stage IIIA legislation concerning exhaust emissions, a new version of the Volvo D9 engine was developed for A25D–A30D.