Tachographs fail: screens die, printers jam, cards get stuck, the unit stops recording altogether. A failed tachograph does not automatically ground the vehicle, but it does start a legal clock, and operators who handle the next few days casually end up trying to reconstruct a week of drivers’ hours from memory. That never ends well. The rules themselves are short and forgiving; almost every enforcement case in this area starts with someone ignoring them, not with the breakdown itself.
The assimilated and AETR drivers’ hours rules are direct about breakdowns. In the event of a breakdown or faulty operation of the tachograph, it must be repaired as soon as possible. And there is a hard backstop: if the vehicle is unable to return to its base within a week, the repair must be carried out en route.
Read that as an operator and the meaning is plain: you get one week of grace to bring the truck home, and no more. A trunking vehicle based in Coventry cannot spend a fortnight tramping around Europe on a dead tachograph and sort it out later. “As soon as possible” governs everything, and the one-week rule is the outer limit of what the law tolerates.
While the tachograph is out of action, the driver must keep a manual record of their activities: driving time, other work, breaks and rest, recorded properly and legibly, day by day. This is not optional admin. GB legislation gives both driver and operator a defence against conviction only in narrow circumstances:
Both defences lean on the manual record existing and being credible. No manual record means no defence, and a manual record written up in the depot on Friday afternoon covering the whole week is exactly what examiners are trained to spot. The same protection applies where a tachograph seal has broken, if the breaking was unavoidable, immediate repair was not possible, and every other part of the assimilated or AETR rules was being followed.
Modern units hold the data, and a dead unit can take the evidence with it. DVSA’s guidance for operators adds a step that fleets forget under pressure: for faults and breakdowns involving digital or smart tachographs, ask the repair centre to download any data held on the unit.
If the centre cannot download it, the centre should issue a certificate of undownloadability, and the operator must keep that certificate for at least 12 months. This small piece of paper is your proof that a gap in the data has an innocent explanation. Without it, a missing fortnight of vehicle unit data looks like something else entirely.
Treat a tachograph failure like a safety defect with paperwork attached:
A tachograph failure is a small event that examiners use as a window into the whole operation. A fleet that handles one cleanly, with dated fault reports, proper manual records, a prompt repair invoice and a certificate where needed, is showing exactly the continuous and effective management the licence undertakings promise. A fleet that produces a shoebox of loose papers is showing the opposite.
The unit will fail eventually; every fleet’s does. The difference between a non-event and an enforcement problem is whether your procedure started the same day.