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Home >> Chrysler >> 2009 >> PT Cruiser Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 58 (DTCS P0299 To P0441) >> P0420-Catalyst Efficiency (Bank 1) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2009 Dodge Caliber. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
EXHAUST SYSTEM LEAK
ENGINE MECHANICAL CONDITION
AGING OR CONTAMINATED O2 SENSOR
O2 SENSOR WIRING AND CONNECTORS
CATALYTIC CONVERTER

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. See  DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure  .