OBD2 Diagnostic Codes
Explore our comprehensive database of 2,798+ diagnostic trouble codes with detailed explanations, symptoms, and repair guidance.
Enter a code like P0420 to see its diagnostic guide, or ask our AI about any code
Browse by Category
OBD2 codes are organized into four main categories based on the vehicle system they relate to.
B - Body
366 codesInterior electronics, body control module, HVAC, lighting, airbags, and comfort systems. Ask our AI for help with B codes.
Common Examples:
C - Chassis
432 codesABS, traction control, stability control, suspension, steering, and brake systems. Ask our AI for help with C codes.
Common Examples:
U - Network
500 codesCAN bus, communication protocols, module interconnections, and network integrity codes. Ask our AI for help with U codes.
Common Examples:
Understanding OBD2 Codes
OBD2 (On-Board Diagnostics II) codes are standardized diagnostic trouble codes used to identify vehicle issues. When your check engine light comes on, your vehicle stores one or more of these codes.
Each code follows a specific format: a letter prefix (P, B, C, or U) followed by four digits. The first digit indicates whether it's a generic (0) or manufacturer-specific (1) code.
How to Use This Database
1. Find Your Code: Use the search bar above or browse by category to find your specific diagnostic code.
2. Review the Guide: Each code page includes symptoms, probable causes, and step-by-step diagnostic procedures.
3. Chat for Help: Need personalized guidance? Use our AI assistant on the home page for real-time diagnostic help.
Important: While our diagnostic guides provide comprehensive information, they are for educational purposes only. Always consult a certified mechanic for professional diagnosis and repair. Improper repairs can be dangerous.
Read Your Codes with an OBD2 Scanner
An OBD2 scanner lets you read and clear diagnostic trouble codes from your vehicle.
Bluetooth scanner with free app - great for beginners
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Budget-friendly handheld scanner
Full-system professional diagnostics
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