verb
to set off, to drive off, to depart
B1
'losfahren' means 'to set off', 'to depart' or 'to drive off'. It is a separable strong verb (fahr‑los) with present stem change a→ä (du fährst). Use sein as auxiliary in perfect (ist losgefahren). Past stem fuhr. Imperatives: Fahr los! Separable prefix moves to sentence end in main clauses.
Examples
Bevor der Bus losfuhr, kontrollierte der Fahrer die Bremsen, damit keine Probleme entstanden.
Before the bus set off, the driver checked the brakes so that no problems occurred.
Ich fahre jetzt los.
I'm leaving now.
Der Zug wird in fünf Minuten losfahren.
The train will depart in five minutes.
Details
Mnemonics
Picture a car with a little flag that says 'LOS!' as it starts rolling
loose + far + hen (imagine a hen driving away)
Notes
Losfahren is separable: in main clauses the prefix 'los' separates (fahre los). For perfect tenses of motion it typically uses 'sein' (bin losgefahren). Intransitive verb; passive forms are not applicable because the verb describes intransitive motion and normally does not take a patient for a true action passive.