Imagine driving along the highway minding your own business and suddenly you get the “check engine” light on your dashboard. This is one of the biggest concerns to almost any driver but in reality it can be something far less intimidating than it first appears to be. In fact, this notification light isn’t meant to indicate a huge issue beneath your hood but indicate to you that something might be wrong (even something insignificant). By having the necessary tools and some basic knowledge you can extract all the needed information to keep your mind at peace. This is where OBD scanners come into play.
Whenever something happens to your vehicle it analyzes the issue and converts it into a “diagnostic trouble code” (also known as DTC). Then that DTC is stored in your on-board computer diagnostic system (also known as OBD). All you need to do after that is have the right equipment to extract that exact trouble code. After you attach your OBD scanner tool to the OBD port you will be able to fetch any codes that the car has stored for you.
In the automotive industry OBD and DTC are often used to describe the same thing, so don’t get confused if you see them used in the same contexts. Also, OBD codes are usually written like that – “OBD2” which is the code type of most cars made after 1996.
Pro Tip: The OBD port is most often located on the driver’s side of the dash near the pedals. It usually has a cover which you have to remove before attaching your scanner to it.
Deciphering An OBD Code
Most scanner tools will display you a combination of 1 letter followed by 4 numbers. This is the actual code you need to look up. Some advanced models like the Wsiiroon Professional OBD2 Scanner will also give you information about that code which will save you a lot of time.
A typical code might look like this:
First Letter – The System
When it comes to the first letter of the code there are four possibilities:
- P – This means that the code is related to the Powertrain. Those are the ones that typically show when you get a “check engine” light
- B – This indicates issues with the Body of the car (including airbags and such)
- C – This letter shows if there is a problem with the chassis
- U – If the error code cannot be defined by the car you will get a code starting with this letter. In most modern cars “U” is used for network communication codes.
There are some professional-grade tools which can identify issues (codes) even further down the car’s systems but they are usually really expensive and can only be found in licensed car shops.
First Digit – The Code Type
This digit shows you whether the code is a generic one (which is the same on all OBD2 compliant vehicles) or a manufacturer specific one.
- 0 – Generic Code (Same for all manufacturers)
- 1 – Manufacturer Specific Code (Their definition is set by the manufacturer)
However, there can be codes like these: P2, P30, C2, C3, etc. These are more advanced and not all OBD scanner tools show them.
Second Digit – The Sub-System
This third number refers to the affected system. It can vary from 1 to 9 and they all have different meanings. Here are the definitions of each one of the numbers:
- 1 – Fuel or Air metering issue. This usually appears when there is something wrong with the Mass Air Flow sensor (MAF).
- 2 – This indicates issues with the fuel injector.
- 3 – This can mean a couple of things but all of them are ignition-related. From our experience most often those are engine misfires.
- 4 – Emissions issues such as catalytic converter efficiency problems.
- 5 – Vehicle speed controls and idle control issues
- 6 – Most often this means internal computer failures (circuit issues)
- 7, 8, 9 – Those all indicate issues with the transmission such as pressure faults and/or sensor problems.
The Third And Fourth Digits
Those last two numbers provide the description of your issue. They are the most specific part of the code and are what the mechanics look at primarily. There are tons of online directories where you can check the specific codes for your car model just by typing it in. That is, of course, if your scanner doesn’t provide that information.
Pro Tip: If you get a long list of fault codes make sure you first address the top ones, as the lower ones may be in direct relation to them.
A Thing To Remember
It is really important to know that obd scanners will reveal you codes which will then lead you to the system that is malfunctioning. Your tools won’t give you the information needed to fix it, nor will it pinpoint the exact issue. That isn’t the purpose of an OBD scanner. The reason people buy them is that they can identify whether the car is giving out false alarms or something more serious is going on. That way, you can save time and money by clearing faulty error codes and not take your car to the mechanic every time a warning light goes off on your dashboard.
You also need to remember that codes can be triggered by some non-harming factors such as:
- Loose fuel cap
- Poor wiring connections
- Moisture messing up the car’s sensors