OBD trouble-code guides built for fast decisions
Clear OBD-II code guides with quick meanings, practical first checks, and safer next steps when a warning shows up on the scanner.
Start with the generic code meaning, then open a manufacturer view when make-specific fault patterns or repair history are more useful.
The current OBD library includes 467 generic code guides, plus manufacturer views where brand-specific notes make the same code more useful to explain differently.
Start typing a code, symptom, or system to see matching guides.
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Manufacturer views
Start with a manufacturer when you want the same code explained with make-aware notes and more brand-specific fault patterns.
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Acura
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Audi
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BMW
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Buick
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Cadillac
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Chevrolet
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Chrysler
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Dodge
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Ford
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GM
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GMC
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Honda
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Hyundai
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Jeep
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Kia
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Lexus
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Lincoln
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Mazda
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Mercedes-Benz
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Mitsubishi
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Nissan
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Porsche
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Ram
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Subaru
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Toyota
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Volkswagen
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Volvo
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FAQ
OBD-II basics worth knowing
What is a generic OBD-II code?
A generic OBD-II code is a standard trouble code used across many makes, not just one manufacturer. Codes like P0300 or P0420 are meant to be readable by any compliant scan tool, even though the final diagnosis can still vary by vehicle.
What do the letters P, B, C, and U mean?
The first letter tells you which system the code belongs to. P is powertrain, B is body, C is chassis, and U is network or communication.
What does the first number after the letter mean?
That digit tells you whether the code is generic or manufacturer-specific. A 0 usually points to a generic code, while a 1 often means the code is make-specific and may need manufacturer-aware guidance.
Are OBD-II codes the same on every vehicle?
Not completely. Generic codes follow shared standards, but manufacturers can add their own codes and sometimes interpret generic faults a little differently in practice. That is why this OBD section starts with generic pages and then adds manufacturer views where the diagnosis meaningfully changes.
How many OBD-II code definitions exist?
There are thousands of defined trouble-code entries across the standards and manufacturer-specific extensions. This site is focusing first on the most common high-volume codes rather than trying to publish every definition at once.