This code means that an invalid combination of tachograph cards has been inserted into slots 1 and 2. The tachograph does not allow certain card types to be used together at the same time.
What’s happening:
Code 29 appears when the tachograph detects a conflict between the two inserted cards. For example, inserting incompatible card types simultaneously will trigger this message.
What drivers should do:
First, remove both cards and check which cards are being used.
Ensure only the correct combination is inserted — typically driver cards in normal operation.
Reinsert the correct card(s) one at a time and confirm the tachograph accepts them.
From a driver training perspective:
Drivers should only insert their own driver card unless specifically instructed otherwise (e.g. inspections or workshops). Avoid inserting multiple cards unless operationally required and clearly understood.
If the issue continues:
There may be a fault with one of the cards or misuse of card combinations. In this case, the vehicle should be checked by an approved tachograph centre.
Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc
