Car Diagnostics

How to Read Car Diagnostic (OBD) Scan Codes

Modern cars are filled with electronics, and one of the benefits of this is that the car can often tell you what is wrong, eliminating lengthy troubleshooting procedures to find the problem.

Running a diagnostic scan on your car can reveal if there are any issues, and if so, what they are. Here’s how it works.

How to Read Car Diagnostic OBD Scan Codes

Since 1996, all vehicles had to have an OBD (On-Board Diagnostics) II diagnostic system, which allows the car to be scanned using universal scanning tools which will produce error codes to tell you what the problem is.

This scan can reveal a wide range of problems all around the car including ignition timing issues, level of buildup in the engine, fuel injector performance, engine rpm levels, coolant temperature, airbag condition, lights and more. Since 1996, the diagnostic system has been further improved and now can tell you almost anything about the car.

The diagnostic tool will generally tell you what the problem is by producing a code. The standard for codes is as follows:

The codes range from P0100 to P1899. Each letter and number in the code represents a different section of the car.

The first letter is often a P, which stands for powertrain (engine, gearbox etc). B stands for the body (includes A/C and airbag), C stands for chassis (includes ABS) and a U stands for Network Code (Wiring Bus).

The number 0 (the second digit) is a generic OBD code shared by most manufacturers, but some use a specific code here so the number 1 may show.

The third digit tells you the category of the problem:

  • 1 means there is an air or fueling problem.
  • 2 means there is something wrong with the fuel injector circuit.
  • 3 means there is a problem with the ignition.
  • 4 means there is an emissions control problem.
  • 5 means there is a vehicle speed or idle control problem.
  • 6 means there is a computer or output circuit problem.
  • 7 or 8 means there is a transmission problem.

The fourth and fifth digits of the specify in detail what system is having a problem. These codes are set by the vehicle manufacturer so you (or the person doing the scan) will need to check with the manufacturer what they stand for.

If you need to have your car scanned to diagnose a problem, call us now on 09 218 7789 or pop into our shop at 597 Rosebank Road today!