OBD2 Trouble Code (DTC) Reference

Look up check engine, ABS, airbag, and network communication codes — and find the right TOPDON scanner to diagnose them.

Diagnostic trouble codes (DTCs) point to the system that failed — not always the part to replace. P-codes cover engine and emissions; C-codes point to ABS and chassis; U-codes indicate CAN network communication faults; B-codes relate to airbags and SRS. Use this reference, then scan with a TOPDON tool that matches the required depth.

P Codes P — Motorisation et émissions 514 codes

C Codes C — Châssis, ABS et stabilité 56 codes

U Codes U — Réseau et bus CAN 86 codes

B Codes B — Airbag et SRS 83 codes

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Questions fréquentes

What are OBD2 trouble codes (DTCs)?
Diagnostic trouble codes point to the system that failed — P-codes cover engine/emissions, C-codes ABS/chassis, U-codes network communication, B-codes airbag/SRS.
Can I diagnose any DTC with a basic code reader?
Basic readers read most P-codes in the engine module. ABS, airbag, and network U-codes often need an enhanced or full-system TOPDON scanner — each code page lists the required tier.