Thinking of buying an OBD scanner? Learn how they work - and how they could save you money in diagnosis and repair bills.

What does OBD stand for?

ODB stands for On-Board Diagnostics scanner. While all garages will have these devices, car owners can also buy them in order to diagnose engine problems.

 

What is an OBD scanner?

An OBD scanner (On-Board Diagnostics scanner) is a device used to diagnose and monitor the health of a vehicle by accessing its on-board diagnostic system. All modern cars (typically those manufactured after 2001 in Europe or 1996 in the U.S.) are equipped with an OBD-II system that tracks performance and detects issues.

 

Key Features of an OBD Scanner:

  1. Error Code Reading: The scanner retrieves diagnostic trouble codes (DTCs) from the vehicle's computer, which indicate specific problems (e.g., engine misfires, oxygen sensor issues, emissions failures).
  2. Live Data Monitoring: Some scanners display real-time information, such as fuel efficiency, engine RPM, or coolant temperature. It’s possible to connect a telematics system to this data stream, meaning fleet managers can monitor things like idle time. However, this isn’t something the general car owner would be concerned with.
  3. Clearing Codes: It can reset warning lights, like the Check Engine Light, after resolving an issue.
  4. Vehicle-Specific Functions: Advanced models may perform deeper diagnostics, for example by testing ABS (anti lock braking), airbag, or transmission systems.

 

Types of OBD Scanners:

  1. Basic Code Readers: Simple and affordable, these provide error codes but offer limited detail. These can be bought online for £20 - £30.
  2. Professional OBD Scanners: These are more expensive, but provide advanced diagnostics, vehicle-specific functions, and data storage.
  3. Bluetooth/Wireless Scanners: Small devices that connect to a smartphone or tablet via apps for easy access to diagnostic information. Some such products may require the buyer to take out a subscription, but most don’t.

 

OBD Scanner

 

How to use an ODB scanner? Where do you plug in the diagnostic tool?

  • Connection: Plug the OBD scanner into the OBD-II port, which is usually found under the dashboard on the driver’s side. It will have either a 16-pin, 9-pin, or 6-pin connection.
  • Communication: It communicates with the car’s ECU (engine control unit or computer) to retrieve data. The ECU is essentially your car’s brain.
  • Interpretation: The scanner or its companion app provides information to help diagnose and address issues. With simpler systems (that don’t come with an app), the user can look up the meaning of codes online.

 

How to use an OBD II scanner?

All petrol cars manufactured for sale in Europe since 2001 have featured “OBD II” standard technology, replacing the original ODB system. Technically, the European version of OBD is called EOBD.

Note that when a technician or mechanic talks about ‘OBD’ they are almost always referring to the OBD II system, unless the vehicle in question was purchased new before 2001.

However, the original OBD system was primarily focussed on emissions, while the OBD II system could monitor emissions and diagnose engine problems. The older system has very limited capabilities.

 

Benefits of using an OBD scanner:

  • Saves you time and money by pinpointing issues without needing a mechanic.
  • Gives you the ability to clear error codes yourself.
  • Useful for pre-purchase inspections of used cars.
  • Helps ensure your vehicle complies with emissions standards.

 

Can using an ODB scanner really save you money?

For those with some mechanical and technical understanding of how their vehicle works, an OBD scanner can potentially save time, money and hassle.

Compared to some maintenance/repair tasks, using an OBD scanner is fairly straightforward. You simply plug it in, retrieve the code, and look up what it means. If the issue is fairly simple, you might set about fixing it yourself, which could save considerable sums compared to paying a technician/garage.

However, many vehicle owners won’t have the time or inclination to purchase such a scanner, then learn how to interpret the codes and carry out repairs. Opting to hire the services of your local garage may be quicker and less hassle (but will be relatively costly).

Note also that your local technician will have invested in a professional OBD scanner and associated equipment, which may be more effective and reliable than cheaper systems bought online which are aimed at car owners.