Q501 4 Cylinder MT Application DTC Troubleshooting Data Version: 0.1 Date: 21-Sep-2018 Prepared By: Mithi Prasad, Sarang Kulkarni, Manish Gupta Checked By: Yogesh Jadhav Approved By: Satish Kumar P Page: 821 of 1052 Copyright © TATA MOTORS Ltd. This document must not be used in any way, such as copying and redistributing to third parties, without the consent of author. P0401-21: EGR “A” Flow Insufficient Detected – The minimum control deviation falls below the lower limit Overview: DTC Description (User Friendly) The minimum control deviation falls below the lower limit ECU Pin Number A067, A088, A040, A079, A078 Customer Symptom MIL ON, CEL OFF Fault Effects (On Vehicle) - Lamp Status (If Any) MIL ON, CEL OFF Fault Detection Condition (Root cause) The limit for the maximum permissible negative control deviation of the exhaust−gas recirculation control is not reached. Normal Operating Condition The limit for the maximum permissible negative control deviation of the exhaust-gas recirculation control is exceeded (healing next driving cycle). Probable Trouble Area Intake or Exhaust system Problem EGR air flow control valve binding EGR System leak EGR Valve Healing Condition Rectify the error Clear through diagnostic tool Ignition OFF & ON Component Details: An incomplete burnt gas in exhaust is return to the cylinder. EGR works by recalculating a portion of an engine's exhaust gas back to the engine cylinder. Intermixing the incoming air with recalculated exhaust gas dilutes the mix with inert gas and in turn reduce the combustion temperatures for reducing NOx emissions. Preliminary Checks: 1. Check whether the customer voice / view about the issue is matching with the fault effects mentioned in above Table. If yes, go ahead with next steps. If not, check for other DTC’s presence. 2. Check whether other customers report similar complaints earlier. If yes, perform the preliminary checks with respect to earlier issue closure.\ 3. Check for any clogging in Inlet Air Circuit. 4. Check for any leakages in EGR flow path. 5. Check whether the EGR valve is physically damaged 6. Check for any Air Mass Flow Sensor / Exhaust related faults presence. If so, rectify them. 7. Check for any faults related to atmospheric sensor. If so, rectify them by following their rectification procedure. 8. Check for damage of pins at ECU connector. Trouble Shooting: Step Checks IF YES IF NO 1 Run the EGR High Pressure DC Motor Test Routine. Is the Routine Result – OK? Go to Next Step Rectify the wiring Harness connections between EGR Valve and EMS ECU. Repeat the Routine Test again.
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