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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 425 (5.7L - DTCS P0205 To P058B - 2500 Hd & 3500 Hd) >> Diagnosis And Testing >> P0420-Catalyst Efficiency (Bank 1) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes 
O2 SENSOR 1/1 RETURN CIRCUIT SHORTED TO GROUND
O2 SENSOR 1/2 RETURN CIRCUIT SHORTED TO GROUND
O2 SENSOR 1/1 RETURN CIRCUIT OPEN
O2 SENSOR 1/2 RETURN CIRCUIT OPEN
EXHAUST LEAK
ENGINE MECHANICAL CONDITION
AGING O2 SENSOR
CATALYTIC CONVERTER

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to  STANDARD PROCEDURE  .