OBD-II Diagnostic Trouble Codes
Look up OBD-II fault codes from your scan tool. Search a code like P0420 or a fault name to see what it means, common causes, and how to fix it.
Powertrain codes cover the engine, transmission, fuel system, emissions controls, and hybrid/EV drive components.
P-codes are the most common codes drivers see when a check engine light comes on. They point to faults in how the engine runs, how fuel and air are managed, how exhaust is cleaned, or how the transmission shifts.
Generic P0xxx codes are standardized across manufacturers. A P0420 on a Ford means the same general fault type as on a Toyota — though the exact repair steps can still differ by vehicle.
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