Complete Guide of On-Board Diagnostic Codes
On-Board-Diagnostic (OBD) Trouble Codes are one way your vehicle reports self-diagnostic results. When the system identifies an issue, it turns on the check engine light and provides real-time data in addition to a standardized series of OBD2 Codes.
What are OBD2 Codes？
On-Board-Diagnostic (OBD) Trouble Codes are one way your vehicle reports self-diagnostic results. When the system identifies an issue, it turns on the check engine light and provides real-time data in addition to a standardized series of Diagnostic Trouble Codes (or DTCs). With a code reader or scanner, you can access one or more OBD2 codes that indicate the issues.
OBD system started in the early 1980s with a simple function to turn on the malfunction indicator light or “idiot light” when it detects a malfunction. The codes varied by manufacturers and make, which made it difficult for mechanics to diagnose the problem.
In 1996, a new specification, OBDII, was made mandatory for all cars sold in the United States. It specifies the type of diagnostic connector and its pinout, the electrical signaling protocols available, and the messaging format. With this standard, OBDII Scanner and OBDII Reader became popular tools that everyone can use to diagnose car malfunctions.
What are Diagnostic Trouble Codes
Diagnostic Trouble Codes (DTC) are the codes generated and stored by the Powertrain Control Module (PCM) when the Onboard Diagnostic (OBD) system indicates a malfunction. Simply put, when your car system diagnoses that something went wrong, it will send a code indicating the specific fault. Following a fault manual issued by the Society of Automotive Engineers (SAE), the DTC Codes tell you what the problem is and helps further diagnosis.
In 1996, a regulation about OBD and DTC codes was made mandatory for all cars sold in the United States. It specifies the standard of OBD ports and a fault code manual for all cars, which is referred to as OBD2. With this standard, it’s much easier to understand the car malfunctions and facilitates some DIY diagnosis and fixes of vehicles.
How Do You Read OBD2 Codes?
There are many tools available to plug into the OBD connector and access the DTCs, varying from simple consumer goods to sophisticated OEM dealership tools. Generally, you will find two types of Car Code Readers or Car Code Scanners available in most online or offline stores:
TOOL 1: Hand-Held Scan Tools
There are many hand-held car code scanner in Home Depot or on Amazon. You can read the codes and sometimes clear the codes with these tools, but the information is limited. You have to record the codes and search for more information before you can do anything.
TOOL 2: Mobile Device-Based Tools
There are many Bluetooth OBD2 Scanners & Readers now on the market that may connect to a phone app or other software. These devices sometimes provide rich information and have a better interface.
Step by Step OBD2 Codes Reading Guide
Here we introduce the guide to read OBD2 Codes using a mobile device-based tool:
Step 1: Locate your vehicle’s OBD port
The OBD-II port is usually located under the dashboard, beneath the steering wheel column (1-3 in the diagram below). If not located beneath the steering wheel column, look for the port in the areas indicated by numbers 4-9.
Step 2: Plug your OBD-II scan tool into the connector
Step 3: Pair your OBD-II Scanner with an App
Download a DTC code scanning App, and turn on Bluetooth to pair with the OBD-II Scanner.
When the scanner is paired with your phone, the App will show the diagnostic results. Use the ZUS App as an example, after creating your vehicle profile and pairing the OBD-II Scanner, you can do the following to get an overview of your vehicle:
- Safety Center & Engine Health Scan
- Decode & Clean Error Codes
- Pro Dashboard & Driving Habits Analysis
- Car Finder & Mileage
With this information, you can get a great overview of your vehicle’s condition, your driving habits, your travel record, and use it to find your car when you forgot where you parked.
How to Interpret Car Diagnostic Codes
The car diagnostic codes, AKA Diagnostic Trouble Codes, consists of a five-digit alphanumeric code. The formats are shown below:
List of Most Common OBD2 Codes
Here is a list of common OBD2 Codes (DTC Codes). Feel free to check them! And if you cannot find your code here, use the Search Bar to do further research.