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Emissions System

Catalytic converter and emissions codes

6 articles in this category

P0420

Catalyst System Efficiency Below Threshold

Everything about P0420 catalytic converter code. Learn if you need a new cat, cheaper fixes, and how to diagnose properly.

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P0430

Catalyst System Efficiency Below Threshold Bank 2

P0430 catalytic converter code for Bank 2. Same as P0420 but for the other side. Learn diagnosis and repair options.

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P0442

EVAP System Small Leak Detected

Fix P0442 evaporative emission system leak. Learn common causes of small EVAP leaks and how to find them.

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P0455

EVAP System Large Leak Detected

Diagnose P0455 large EVAP leak code. Find out what causes large evaporative system leaks and how to repair.

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P0401

EGR Insufficient Flow Detected

Fix P0401 EGR flow code. Learn about the exhaust gas recirculation system and how to restore proper flow.

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P0421

Warm Up Catalyst Efficiency Below Threshold Bank 1

Understand P0421 catalyst code. Learn about warm-up catalyst monitoring and efficiency testing.

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