OBD 2 Code List (2024)

Introduction to OBD 2 Codes

OBD 2 codes, also known as Diagnostic Trouble Codes (DTCs), are alphanumeric combinations that provide valuable insights into a vehicle’s condition. These codes act as a language that vehicles use to communicate potential issues, making them a vital tool for car owners, mechanics, and automotive DIYers alike.

Some of the codes are universal, meaning all car makes will use the same codes for the same conditions, while others are make-specific. Generally, the better the scan tool, the more capable it will be to retrieve a wide selection of codes.

When a warning light appears, visit your nearest AutoZone store to get your diognostic report with our free Fix Finder Service. AutoZone’s friendly staff will provide a clear report based on technician-verified fixes, identifying the issue and recommending solutions and parts for repair. Trust AutoZone’s Fix Finder service to swiftly diagnose your vehicle’s issues and get you back on the road confidently.

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Understanding the OBD 2 System

The OBD 2 system is a standardized system present in most vehicles manufactured after 1996 in the United States. Interestingly, its primary purpose is to monitor and report the performance of various vehicle components, ensuring they meet emission standards.

One of the core components of OBD 2 is the ECU or electronic control unit, which constantly monitors sensors and components throughout the vehicle. When a problem is detected, the ECU generates a DTC, providing a code that signifies the nature and location of the issue.

How to Retrieve OBD 2 Codes

Retrieving OBD 2 codes is relatively straightforward, thanks to the universal OBD 2 port found in all compatible vehicles. To access these codes:

Locate the OBD 2 port. This port is typically located beneath the dashboard, near the driver’s seat. It may also be found under the hood in some vehicles.
Plug in a scanner. Use an OBD 2 scanner, readily available at AutoZone, or consult your vehicle’s manual to determine if it has a built-in diagnostic tool.
Read the codes. Once connected, the scanner will communicate with your vehicle’s ECU and retrieve any stored DTCs.

Interpreting OBD 2 Codes

Understanding OBD 2 codes is essential to assess your vehicle’s condition accurately. These codes are structured as a series of letters and numbers, with each character serving a specific purpose:

First character (P, C, B, or U). This character indicates the system associated with the fault.
Second character (0-9). Specifies the specific fault within the system.
Third and fourth characters (0-9). Provide additional information about the fault’s location or nature.
Fifth character (0-9). Indicates the severity of the issue.

Common OBD 2 Codes and Their Meanings

OBD 2 codes are categorized into four main groups, each represented by the first character in the code.

P0xxx – Powertrain Codes

Powertrain codes primarily relate to engine and transmission issues. Common examples include:

P0300: Random/Multiple Cylinder Misfire Detected
P0420: Catalyst System Efficiency Below Threshold

C0xxx – Chassis Codes

Chassis codes pertain to issues with the vehicle’s chassis and related components – meaning mechanical systems that aren’t powertrain like steering, braking, and suspension. Examples include:

B0xxx – Body Codes

Body codes involve problems with various interior and exterior components. Some examples include:

B0020: Front Passenger Side Deployment Loop Resistance High
B1000: Electronic Frontal Sensor Data

U0xxx – Network Codes

Network codes indicate communication issues between different vehicle systems. Most of these are manufacturer specific. Common examples include:

U0073: Control Module Communication Bus A Off
U0140: Lost Communication with Body Control Module

While OBD 2 codes provide valuable information, they’re just the starting point for diagnosing and resolving vehicle problems. Here are some essential tips to help you address issues effectively:

Refer to your vehicle manual. Your vehicle’s repair manual often includes information specific to your make and model, which can help you understand the codes better. If you need a resource, check out ALLDATA.
Consult with a professional. If you’re unsure about the problem or lack the necessary tools, consider consulting a qualified mechanic who can diagnose and fix the issue. Seek out one of our Preferred Shops to help you do the job.
Regular maintenance. Keep up with routine maintenance to minimize the chances of triggering OBD 2 codes due to neglect.
Check for recalls. Some issues may be covered by manufacturer recalls or warranties, so it’s worth checking with your vehicle’s manufacturer.

OBD 2 Code List Reference

For your convenience, here’s a comprehensive list of common OBD 2 codes along with their descriptions:

Powertrain Codes

P0300 – Random/Multiple Cylinder Misfire Detected

P0420 – Catalyst System Efficiency Below Threshold

P0171 – System Too Lean (Bank 1)

P0128 – Coolant Temperature Below Thermostat Regulating Temperature

P0442 – Evaporative Emission Control System Leak Detected (Small Leak)

Chassis Codes

C0035 – Left Rear Wheel Speed Sensor Circuit

C1214 – Brake Control Relay Contact Circuit Open

C0036 – Right Front Wheel Speed Sensor Circuit

C0561 – ABS Brake Control Module System

Body Codes

B0020 – Front Passenger Side Deployment Loop Resistance High

B1000 – Electronic Frontal Sensor Data

B1200 – Climate Control Push Button Circuit Open

B1325 – Oil Pressure Sensor Circuit

B1422 – Seat Belt Pretensioner Deployment Control Circuit

Network Codes

U0100 – Lost Communication with ECM/PCM A

U0121 – Lost Communication with Anti-lock Brake System (ABS) Control Module

U0073 – Control Module Communication Bus A Off

U0140 – Lost Communication with Body Control Module

U0401 – Invalid Data Received from Engine Control Module (ECM)

Armed with this information, you should be better prepared to decipher the DTCs your car throws at you. If you need a code reader, parts to fix the problem, or trustworthy advice, shop at AutoZone.

FAQ/People Also Ask

What are OBD2 codes?

They standardized diagnostic trouble codes used to identify issues in a vehicle’s various systems.

How do I read OBD 2 scanner codes?

You need an OBD 2 scanner tool that connects to your vehicle’s port, and then you can retrieve and interpret the codes displayed on the scanner’s screen or through a compatible app.

What is my engine code?

Your engine code is the eighth digit in your VIN number, but it’s not the same as a powertrain-related DTC that’s also referred to as an engine code sometimes.

Does the OBD 2 work with all cars?

OBD 2 is designed to work with most cars manufactured after 1996 in the United States and some vehicles in other regions.