What it means: a security breach message on card slot 1. The card was swapped without a proper closure, it's missing when the unit expected one, or the physical card interlock is open.
Can you keep driving: yes, but log manually while it persists.
What fault 43 means
The smart tachograph doesn't just check whether a card is present, it also watches whether the card and the slot behave as expected. Fault 43 is a security message: the unit detected something unexpected about the card or the slot itself, not a simple reading problem.
Specifically it covers one of three situations: the card was swapped without the previous session being closed correctly, the card is missing at a moment the unit expected one, or the physical lock on the card slot (the interlock) is open.
The difference with 41
41 and 43 are both card-related but not the same thing. 41 is a communication fault: a card is present but the unit and the card aren't talking to each other properly, usually a dirty contact. 43 is about the card or the slot behaving unexpectedly, not about a failed conversation with a card that's correctly inserted. For 41 the fix is usually cleaning the chip; for 43 the first step is checking the card is fully and correctly inserted.
Can you keep driving
Yes, with the same two obligations as any malfunction: the company has it repaired as soon as possible, and you log manually.
What to log right away
While the tachograph is unserviceable or malfunctioning, the driver shall mark data enabling him to be identified (name, driver card or driving licence number), including a signature, as well as the information for the various periods of time which are no longer recorded or printed out correctly by the tachograph: (a) on the record sheet or sheets, or (b) on a temporary sheet to be attached to the record sheet or to be kept together with the driver card.
Regulation (EU) No 165/2014, Article 37(2).
If reinserting the card doesn't clear the fault, start the manual record immediately: your name, driver card or licence number, a signature, and your driving and rest times from the moment the fault appeared.
Who has to fix it, and by when
In the event of the breakdown or faulty operation of a tachograph, the transport undertaking shall have it repaired by an approved fitter or workshop, as soon as circumstances permit. If the vehicle is unable to return to the transport undertaking's premises within a period of one week calculated from the day of the breakdown or of the discovery of defective operation, the repair shall be carried out en route.
Regulation (EU) No 165/2014, Article 37(1). Accessed 25 September 2026.
The repair obligation sits with the company, not with you.
What it costs
The regulation doesn't set a price for the repair itself, that depends on what the workshop finds: a reset, a cleaned interlock, or a replacement card if the card turns out to be the cause. Keep your manual record until the fault is resolved and logged.
Also read
Sources
- Regulation (EU) No 165/2014 on tachographs in road transport, Article 37, consolidated version. EUR-Lex
- VDO DTCO 4.0, manufacturer's official Message summaries: code 043 — "Security breach (drawer 1)".
Legal text quoted verbatim from the consolidated English version published on EUR-Lex, accessed 25 September 2026. VDO does not publish an official fault-code glossary in English; the plain-language description above is our own translation of the manufacturer's documentation, the legal citation is not.
Stuck? See where there is still room.
Drivers report what they see themselves. Parking full, traffic, hazard, roadworks. Open the app and stop driving alone.