CITROEN DS4 Owner's Handbook Manual page 242

Diesel engines
The various caps and covers allow access for
checking the levels of the various fluids, for
replacing certain components and for priming
the fuel system.
1. Power steering reservoir.
2. Screenwash and headlamp wash reservoir.
3. Coolant reservoir.
4. Brake fluid reservoir.
5. Battery/Fuses.
6. Fusebox.
7. Air filter.
8. Engine oil dipstick.
9. Engine oil filler cap.
10. Priming pump * .
11. Bleed screw * .
* According to engine.