These instructions apply to the Mercedes E-Class Mk5 (W213) 2016-2023.
For other models, please choose your vehicle here.
On a diesel Mercedes E-Class W213 the AdBlue (DEF) filler sits under the fuel flap, next to the diesel filler. The tank holds about 23.5 liters and has an automatic anti-overfill cut-off.
Refill as soon as the display warns, because the engine will not restart once AdBlue runs out.
How to refill AdBlue on the E-Class
- Turn the ignition off and open the fuel filler flap.
- Unscrew the blue AdBlue cap (separate from the diesel cap).
- Use a station AdBlue pump or a pouring bottle/canister that meets ISO 22241.
- Fill until the automatic cut-off stops the flow; do not add more after it cuts off.
- Refit the AdBlue cap and close the flap.
Only use AdBlue that meets ISO 22241, and never put AdBlue in the diesel tank or diesel in the AdBlue tank. If the car has already shut down for empty AdBlue, adding several liters and switching on the ignition lets the system recover.
How much AdBlue does a Mercedes E-Class take?
The W213 AdBlue tank holds about 23.5 liters. A top-up from the dashboard warning is usually a few liters, not a full tank.
Where is the AdBlue filler on the E-Class?
Under the fuel filler flap, beside the diesel filler, with its own blue cap. There is no separate AdBlue flap on the W213.
If a warning light stays on or a fault code appears afterwards, you can look the code up free on autodtcs.com.
Independent guide — not affiliated with Mercedes. Always follow your official service manual and safety precautions. Read our full disclaimer.