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P0420

Overview

Code

P0420

Code Type

P

Code Class

P0

System

Engine

Severity Level

Medium

Emissions Related

true

Drivability Impact

None

Diagnostic Protocol

OBD2

Freeze Frame Useful

true

Code Definition

Diagnostic trouble code P0420 indicates catalyst system efficiency below threshold (Bank 1)

Symptoms

Check Engine Light

Overview applies to this diagnostic code.

Affected Systems

On This Page

  • Code Definition

  • Symptoms

  • Affected Systems

  • Possible Causes

  • Diagnostic Steps

  • Drive Safety Notes​

More Resources

Catalytic converter efficiency monitoring

Possible Causes

Failing catalytic converter

Diagnostic Steps

1 Monitor upstream/downstream O2 sensors; 2 Inspect exhaust for leaks

Drive Safety Notes

Vehicle may fail emissions test

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