An On-Board Diagnostics System (OBD) is a computer system inside a vehicle, that tracks and regulates a car's performance. It collects information from sensors inside the vehicle, to alert the user to a problem, often before it becomes a major issue.
From the 21st June, OBD testing will become an inspection item in the NCT. It will be introduced on a phased basis. Initially, when an OBD error code is detected it will result in the vehicle receiving an “Advisory Pass”. Then, from early 2022, when an error code is detected, this may constitute a reason for “failure”.
The inspection is quick and easy, the NCT Vehicle Inspector will plug the OBD scanner into the vehicle's OBD computer port known as the DLC (data link connector). This port is usually located under the steering wheel but may also be found in the glove compartment of the vehicle.
This OBD scanner will quickly indicate whether or not error codes exist, and it also helps and alerts the Vehicle Inspector to possible defects within the vehicle.
In order for the NCTS to conduct the inspection, we ask customers to ensure:
- Their glove compartments are unlocked and clear of personal belongings before their NCT.
- That any devices using the OBD port in the vehicle are removed in advance of the NCT.
The OBD scanner will scan the OBD system for:
- Vehicle Identification Number (VIN)
Using the OBD scanner, the Vehicle Inspector will verify that the VIN read by the OBD scanner matches the number on the vehicle. While a difference will not be a reason for failure, the OBD VIN reading will be recorded on the VIR (Vehicle Inspection Report) issued to the customer.
- Odometer Reading
The Vehicle Inspector will record the odometer reading at the time of the test. They will also verify the reading using the OBD scanner and customers will be alerted to both readings on their VIR report.
- Electronic Braking System (EBS)
Any error code associated with the electronic braking system will be recorded on the Vehicle Inspection Report (VIR) provided to the customer following their NCT inspection.
- Anti-lock Braking System (ABS)
Any error code associated with the antilock braking system will be recorded on the Vehicle Inspection Report (VIR) provided to the customer following their NCT inspection.
While, initially, vehicles with error codes will be recorded as ‘Advisory Pass’, the NCTS strongly recommends that any error codes be addressed by the vehicle repairer. However, the vehicle will not need to return for re-inspection, for these items alone.
From early 2022, should certain error codes be detected, they will constitute a reason for failure in the NCT and an NCT certificate will not be issued until the items are rectified and a pass result is achieved.
We recommend you liaise with your local garage/ mechanic who should be equipped with the necessary diagnostic equipment to perform this scan in advance of going for an NCT.
- Escalation of Defects
The new NCT manual identifies that, where a combination of deficiencies is recorded in the NCT in one area of a vehicle, the combination of deficiencies could lead to the result of the NCT being escalated to ‘fail dangerous’.
An example of one such combination is the inspection item, Brake Pedal. If the following 3 major defects appear on the overall test result, the result will be escalated to fail dangerous:
- Pedal travel is excessive, obstructed or insufficient reserve travel.
- Brake control not releasing correctly.
- Travel in the brake pedal indicates air in the brake system or brakes are in need of adjustment
In such instances, the deficiencies are considered to constitute a direct or immediate risk to road safety and the vehicle should not be driven on the road under any circumstances, in accordance with The Road Traffic (National Car Test) Regulations 2017, S.I. 415 of 2017.
For more information on these changes please see our FAQ
For further information on the items inspected in the NCT, please refer to the NCT Manual