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Nexon Gasoline – EMS ECU Bosch
DTC Troubleshooting Manual
Version: 0.1
Date: 26-08-2017
Prepared By: Sunu S Babu/Yogesh Jadhav
Checked By: Yeshwant Jadhav
Approved By: Satish Kumar
Document Part No: 2921 02 224 A1736
Page: 665 of 1203
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.
P0531-21: A/C Refrigerant Pressure Sensor “A” Circuit Range/Performance - Signal Stuck Low
Overview:
ISO Code
P0531-21
Customer Symptom
Wrong indication of AC pressure
Fault Effects (On Vehicle)
AC Pressure parameter value will be faulty, AC will not
Function. Wrong indication of AC pressure
Lamp Status (If Any)
CE lamp ON after 3 drive cycles
Fault Detection Condition
This fault gets logged if the AC Pressure Signal pin of EMS
ECU is short Circuited to ground.
Normal Operating Condition
Healthy Wiring Harness connections between EMS ECU and
AC Pressure Sensor.
Probable Trouble Area
Wiring Harness connections, Faulty Sensor
Healing Condition
Check Engine Lamp off after 1 driving cycle of fault
rectification
Fault Permanent Deletion
1. Clear DTC Command form Scan tool
2. Stack Over Flow.
3. 40 warm up cycles.
4.ECU flashing
5. ECU power fail
Component Details:
AC pressure Sensor consists of a silicon chip mounted inside a reference chamber. On one side of the chip is the
reference chamber and on the other side is the pressure to be measured. The electrical resistance of the chip varies
with the variation of pressure. This change in resistance alters the voltage signal.
Preliminary Checks:
1) Loose/ Damaged Connections between Sensor and EMS ECU.
2) Check for back out of pins at both Sensor connector and ECU connector.
3) Check for damage of pins at both Sensor connector and ECU connector.
4) Check the continuity from Sensor connector pins to the ECU pins.