Tampering
Tachographs can be tampered with in various ways, such as slightly twisting the marker, blocking the path of the arm with a piece of rubber or foam, short-circuiting the unit for short periods, or interrupting the (older analogue) tachograph's power supply with a blown fuse to stop operation completely thus recording no information whatsoever. There is also "forgetting to insert" the chart when beginning duty and unauthorized changing of the discs are known throughout Europe.
Ghosting is another common trick when false driver information is entered onto a second chart to give the appearance that there is a second driver present in the cab for long distance runs that cannot be completed within a single driver's daily driving period.
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