In the en_US.UTF-8 locale, you cannot type the Euro character by simultaneously pressing the AltGraph and E keys.
Workaround: Choose one of the following workarounds.
Press and release the Compose key, then press and release the C key, then press and release the = key (Compose+C+=).
If your keyboard does not include the Compose key, then press the Control key while you press the Shift and T keys (Ctrl-Shift-T).
Press the Alt key while you press the 4 key (Alt-4).