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: 605 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. P00BD-22: Mass or Volume Air Flow “A” Circuit Range / Performance – Air mass meter sensitivity drift (signal above upper limit) Overview: DTC Description (User Friendly) Air mass meter sensitivity drift (signal above upper limit) ECU Pin Number K086, K076, K087 Customer Symptom MIL ON Fault Effects (On Vehicle) - Lamp Status (If Any) MIL ON. MIL OFF: After 3 warm up Cycles (Drive Cycle with coolant temperature increase by 22 degrees) or Clear DTC Command with fault condition no more present. Fault Detection Condition (Root cause) When the air flow meter measures an air flow rate greater than the internal ECU calculated mass by gas equation of at least 20% Normal Operating Condition Air Mass flow sensor input is in between the upper and lower limits Probable Trouble Area 1. High resistance in the fused main relay supply circuit to MAF sensor 2. High resistance in the MAF sensor signal (Air Flow / Temperature) circuit. 3. High resistance in the MAF sensor ground circuit 4. Intake Air system leak / restriction 5. EGR System leak 6. MAF sensor 7. EMS ECU Healing Condition Rectify the error Clear through diagnostic tool Ignition OFF & ON Component Details: The operating principle is based on the heating of a diaphragm (sensitive element containing two resistances upstream and downstream of the support) in a by-pass duct through which the engine intake air flows. The hot film membrane is maintained at constant temperature (about 120 °C higher than the incoming air temperature) by the specific heating resistance controlled by the management electronics. The mass of air passing through the by-pass duct, giving off heat to the membrane, thermally unbalances the two resistances to an extent directly proportional to the mass of the incoming fluid, an imbalance that is translated through the control circuit into a resistance variation, electronically processed and translated into a frequency value to be sent to the engine management control unit. The imbalance in the resistance value also makes it possible to determine the direction of the column of air. As far as the air temperature information is concerned, it is sent to the engine management control unit via a dedicated pin in the form of a duty cycle signal (rectangular wave). The value of the duty is proportional to the value of the temperature. 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 other faults presence related to ECU Internal power supplies; Follow rectification process for those faults, before proceeding further.
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