Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1 Date: 23/11/2022 Author: ERC Page 127 of 834 Copyright by TATA MOTORS Ltd. This document must not be used in any w ay, such as copying and redistributing to third parties, w ithout our consent P0421 -00- Catalyst 1 Efficiency Below Threshold Bank 1 Overview: Code Cause Effect on Vehicle Fault Code: P0421 -00 1. DOC not functioning properly 2. DOC poisoned – Oil entry from Turbo 3. Problem with DPF-in Temperature sensor 4. Exhaust gas leakage 5. Inverse connection of T5 sensor connector 1.CE Lamp ON 2.DOC temperature won’t rise 3.Reduced vehicle performance 4. Disabled drive mode option Lamp status: Check Engine Lamp on Malfunction Indicator Lamp off Checkpoints: 1. Check Battery Voltage at Ignition off (Nominal Range 11.5V ~ 12.8V) 2. Check for any electrical faults related to catalyst temperature sensors. If present, it must be addressed first Trouble Shooting Steps: Sr. No. Steps Specifications Step 1 Check if DPF inlet temperature sensor is connected properly. Remove and reconnect again properly. - Step 2 Check catalyst temperature sensors physically for any damage or oil deposits - Step 3 Check whether catalyst temperature sensors (DPF inlet temperature sensor – T5 sensor) reading correct value. Check whether the sensor connector is inversely connected. If so, correctly connect the connector and verify the fault behavior In general driving, temperatures should be operating between 150 deg C to 450 deg C Step 4 Check for Exhaust leakage. Arrest, if leaking - Step 5 Check for physical obstruction in exhaust path or oil deposits in DOC inlet. If oil deposits are observed, check the turbo charger for oil throw. Clean the exhaust lines with compressed air not more than 2 bar
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