Powertrain Emissions Diagnostic Trouble Codes

Complete list of Powertrain emissions DTC codes with free diagnostic guides.

Below you'll find every known DTC code for the Powertrain Emissions subsystem with step-by-step diagnostic and repair instructions. 4 guides are available — covering causes, symptoms, and repair costs. Use the table to find your specific code, or browse our full Powertrain DTC code library for other subsystems.

DTC Code Meaning Severity Time

P0402 The engine control module (ECM) has detected that more exhaust gas is being reci... medium 30-60 minutes P0411 The engine control module (ECM) has detected that the secondary‑air injection (S... medium 30-60 minutes P0420 The P0420 code means your catalytic converter is not cleaning exhaust gases as e... medium 30-60 minutes P0451 The engine control module has detected that the EVAP‑system pressure sensor is r... medium 30-60 minutes

About Powertrain Emissions Trouble Codes

Powertrain emissions diagnostic trouble codes are triggered when the vehicle's onboard computer detects a malfunction in the emissions subsystem. These codes help you quickly identify the problem without visiting a dealership. Our guides walk you through each DTC code with step-by-step diagnostic procedures, tools needed, and when to call a professional mechanic.

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