Yellow flag

A single waved yellow flag warns of danger ahead — drivers must slow down and cannot overtake until the hazard is passed.

Yellow is shown for anything from a car stopped off-line to debris on the racing surface. Overtaking is forbidden through the affected sector, and drivers are required to demonstrably reduce speed, not merely lift for a moment.

Ignoring a yellow is treated seriously because marshals are often on or near the track. Time deletion in qualifying is the usual penalty; in a race it can be a time penalty or worse.