VDO Tachograph Error Codes

This code means that the VDO tachograph is unable to communicate with the DSRC module.
Code 85 is generated when communication between the tachograph head unit and the DSRC (Dedicated Short-Range Communication) module fails. DSRC is used for remote early detection checks by enforcement authorities, allowing certain tachograph data to be read wirelessly without stopping the vehicle.
This fault is only applicable to DTCO 4.0 and 4.1 tachographs and does not affect earlier versions.
The issue is treated as a system communication fault, not a driver-related problem. The tachograph itself may not be defective — the problem can originate from the DSRC module or its connection.
Common causes include:
Communication errors between the tachograph and DSRC unit

Faulty or damaged DSRC components

Wiring or power supply issues affecting the DSRC module
If Code 85 appears, drivers may attempt to turn the vehicle ignition off and back on. If the issue persists, the DSRC system should be checked and any defective components replaced. Because this involves secure tachograph communication systems, the vehicle should be referred to an approved tachograph centre for proper diagnosis and repair.
🔗 Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

This code means that the VDO tachograph has detected a journey being made without a valid driver or workshop card in card slot 1, or with an invalid combination of cards in slots 1 and 2.
Code 28 is generated when the tachograph records vehicle movement but cannot associate it with a valid card. This is usually a card usage issue rather than a driver behaviour or technical fault.
Common causes include a driver starting a trip without inserting their driver card, inserting the wrong type of card, or a company or control card being left in card slot 1. An invalid combination of cards across both slots can also trigger this code.
Trips recorded while Code 28 is active may be logged as driving without a card, which can create compliance issues if not identified and addressed.
If Code 28 appears, check that a valid driver or workshop card is correctly inserted and that company or control cards are not in card slot 1.
If Code 28 continues to be displayed after the cards have been checked, the vehicle should be referred to an approved tachograph centre for investigation, as there may be an issue with the tachograph or card reader.
https://www.gov.uk/find-approved-tachograph-centre-atc

Error 20 relates to a motion sensor fault, which can affect how vehicle movement, speed and distance are recorded and will cause issues during roadside checks or compliance reviews.

To make sure this is a genuine fault, drivers should turn the vehicle ignition off and back on and see if the error clears. Additionally drivers can check the cables connected to the tachograph for loose or incorrect connections.

If the error remains, the vehicle should be checked at an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

Further details on the error can be found here:
https://www.dtco-user.com/errorcodes/2.0/index.php?lng=en&site=20-29

Code 83 relates to a GNSS (satellite positioning) signal fault. This means the tachograph is not receiving a valid GNSS signal, or it is unable to obtain position data.
GNSS is used by the tachograph to record location information, so if the signal is missing or interrupted, the unit may not be able to log position events correctly.
In most cases, Code 83 is not a complete tachograph failure, but it does indicate that the system cannot reliably detect a satellite signal.
Common causes include:
No GNSS signal being received (poor satellite coverage)

No position data available

Incorrect DTCO 4.1x configuration

Faulty GNSS antenna or related components

What to do if Code 83 appears:
Drivers should first check whether the vehicle is in an area with limited satellite reception (such as tunnels, underground parking, or dense urban areas). If the fault continues when the vehicle is back in open sky conditions, further checks may be required.
Recommended actions include:
Checking GNSS function

Checking and correcting DTCO 4.1x configuration if required

Replacing any defective components

If Code 83 remains active, the vehicle should be referred to an approved tachograph centre for diagnosis and repair, as GNSS faults may require inspection of the antenna, wiring, or internal tachograph system.
🔗 Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

This code means that the workshop card inserted in drawer 1 (driver 1) is blocked.
Code 052 is shown as an operational message and indicates that the inserted workshop card cannot be used.
In most cases, this happens because the workshop card has been blocked after five unsuccessful PIN entries. It may also appear if the workshop card is defective.
If Code 052 appears, the workshop card should be checked and a valid (not blocked) workshop card must be inserted in order to proceed. If the card remains blocked or is suspected to be defective, it should be assessed by an approved tachograph centre.
🔗 Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

This code appears after an uninterrupted driving time of 4 hours 30 minutes. The DTCO 4.1x warns the driver that the required break must now be taken.
Code 074 is triggered when no legal minimum period of rest has been recorded within the permitted driving period.
If Code 074 appears, the driver must find a suitable place to stop and observe the required break in accordance with drivers’ hours regulations.

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

This code means the tachograph has detected that there is no paper in the printer during a printout or print request.
Code 39 is generated when the DTCO determines that the printer roll is missing or has been fully used. If this happens during an active printout, the print is interrupted and the previously printed section is automatically marked. If it occurs during a print request, the request is rejected.
Common causes include:
No printer paper inserted
All printer paper has been used
If Code 39 appears, the driver should check whether there is paper in the printer and insert a new roll if necessary.
If a new roll is inserted within one hour, the DTCO 4.1x will automatically continue the interrupted printout. The first two lines of the subsequent printout will show:
Line 1: Starting time of the original printout
Line 2: Counter of the successive prints
If the message continues to appear after inserting a new paper roll, the vehicle should be referred to an approved tachograph centre for further inspection.
🔗 Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

Code 12 indicates that a communication fault has occurred while downloading data from a driver card or the vehicle unit (VU).
In simple terms, the tachograph and the download equipment were unable to communicate properly during the download process.
What this means for Transport Managers and Operators:
This code commonly appears during routine card or vehicle downloads. It does not automatically mean the tachograph is faulty, but it does mean the download was unsuccessful and must be repeated to remain compliant.

You should:

• Repeat the download process
• Check the connection cable for loose fitting or visible damage
• Try a different download lead or download device if available
If the issue continues:
Further checks of the tachograph download interface or internal components should only be carried out by an approved tachograph centre.
🔗 Find an approved tachograph centre (ATC):
https://www.gov.uk/find-approved-tachograph-centre-atc

Consistent download failures can put your compliance at risk, so always act promptly and escalate to an ATC if basic checks do not resolve the issue.

This code appears when an issue is found with the date links when reading the tachograph card in drawer 2.
Code 67 points to a potential issue with the tachograph card’s data structure. It does not automatically mean tampering — but it does require attention and proper checks.
Drivers should:
– Remove and reinsert the card to rule out a temporary read error.
– Check the card for visible damage (chips, cracks, contamination).
– If available, try the card in another vehicle unit to confirm whether the issue follows the card.
If the error remains after basic checks:
– The card should be assessed.
– Further technical analysis should be carried out by an approved tachograph centre.
🔗 Find an approved tachograph centre:
https://www.gov.uk/find-approved-tachograph-centre-atc

As always, ensure drivers are trained to report fault codes immediately and not ignore operational messages. Early reporting protects both the driver and the operator.