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Home >> Jeep >> 2023 >> Grand Cherokee Altitude, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 44 (2.0L - DTCS P0401 To P04C1) >> DTC Troubleshooting >> P0420 Catalyst System Efficiency Below Threshold Bank 1 >> Possible Causes

Possible Causes

WARNING: This page is about a different variant/trim than selected.
Possible Causes
EXHAUST LEAK
ENGINE MECHANICAL CONDITION
AGING OR FOULED UPSTREAM O2 SENSOR
CATALYTIC CONVERTER

Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding. Refer to  PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE  .