For transport operators, planning is everything. Vehicles are scheduled, routes are allocated, customers are expecting deliveries, and every minute counts.
In such a tightly managed environment, unexpected equipment failures can be particularly disruptive. One of the most critical—and most inconvenient—issues an operator can face is a tachograph malfunction.
A defective tachograph is not only a barrier to efficient fleet management; it immediately raises legal and compliance concerns. It’s an issue no operator wants to deal with, but it is one that most fleets will face at some point.
When it does, the questions are immediate: how long can you legally keep driving with a defective tachograph, and how quickly does it need to be repaired to stay compliant?
Keeping Moving – How long can you continue to drive the vehicle?
A defective tachograph does not necessarily mean an immediate stop. The law recognises that unexpected defects can occur and allows a short, controlled window in which the vehicle may continue to operate.
The law is clear: the repair must be organised and completed as soon as possible. However, you can keep driving for up to 7 days, if it is not practicable to get the tachograph repaired sooner. This is intended to allow operators enough time to either return the vehicle to the operating centre or to reach an approved workshop for inspection and repair.
This flexibility is useful, but it comes with responsibilities.
When driving a vehicle with a defective tachograph unit, the driver must keep accurate manual records of all their activities, and all other aspects of the assimilated / AETR drivers’ hours rules must be complied with.
Manual Record Keeping Is Mandatory
While the tachograph unit is defective, the driver must keep detailed manual records of their activities, covering:
- Driving
- Other work
- Periods of availability
- Break & rest periods
These manual entries replace the automatic digital or smart tachograph recordings and are a legal requirement. Failure to keep accurate written records can lead to enforcement action, even if the defect itself was unavoidable.
How quickly do you need to get the tachograph fixed?
The tachograph must be fixed as soon as possible.
Operators have a legal responsibility to make sure that the tachograph equipment is maintained in proper working order. To demonstrate compliance, operators should follow best practice steps:
- Book the vehicle in immediately at an approved tachograph centre for the soonest possible time
- Provide the driver with evidence of the booking, such as an email confirmation or printed appointment details, in case they are stopped on route.
- Record the fault The faulty tachograph should be recorded as a vehicle defect on the drivers walkaround check report. You should follow your usual defect report management procedures. Record updates of the action taken alongside the record. Multiple updates as the defect is managed up until its repair is useful; record when the defect is assessed by a manager, when the tachograph centre booking is made and once the rectification is complete.
This documentation provides clarity if enforcement officers ask why the vehicle is operating with a defective unit.
If the vehicle is unable to return to the operating centre within a week, it must be repaired whilst away.
Loss of Data from Digital or Smart Tachographs: Managing the Risk
Digital and smart tachographs store essential data about vehicle movements and drivers’ activities. Operators are legally required to download, store, and retain this information.
If the tachograph unit fails, there is a real risk of partial or total loss of data. Operators must take the correct steps to manage this risk and protect the business.
During the repair process, you should ask the tachograph repair centre to download the vehicle tachograph data.
Certificate of Undownloadability
If download attempts fail, make sure you receive a Certificate of Undownloadability – this is an official document issued by a tachograph centre that confirms that data could not be extracted due to a genuine technical problem.
Whether the vehicle unit was downloaded 1hour ago, 1 day ago or 89 days ago, failing to have the data is a breach of your legal requirements – but the certificate of Undownloadability explains the missing data is due to a technical issue.
The Certificate of Undownloadability must be retained for at least 12 months.
A tachograph failure is inconvenient, but it does not have to cause major disruption. The regulations offer operators a short and controlled period—up to 7 days—during which the vehicle can continue operating while repairs are arranged.
By acting quickly, keeping accurate manual records, documenting every step, and safeguarding tachograph data, operators can stay compliant, minimise downtime, and protect their business from enforcement action.