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NOx Sensor Communication Error Fix

The document outlines the diagnostic process for a U029D-00 DTC code related to lost communication with the NOx Sensor 'A'. It details the probable causes, effects on the vehicle, and a series of remedial actions including inspections and checks for continuity, resistance, and voltage. Additionally, it provides visual inspection guidelines and methods for determining whether issues lie within the wiring harness or the sensor itself.

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Shree Kanade
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435 views4 pages

NOx Sensor Communication Error Fix

The document outlines the diagnostic process for a U029D-00 DTC code related to lost communication with the NOx Sensor 'A'. It details the probable causes, effects on the vehicle, and a series of remedial actions including inspections and checks for continuity, resistance, and voltage. Additionally, it provides visual inspection guidelines and methods for determining whether issues lie within the wiring harness or the sensor itself.

Uploaded by

Shree Kanade
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Component DTC Code Error code description

Pre SCR NOx


U029D-00 Lost Communication With NOX Sensor "A"
Sensor1

Sensor location Sensor view

It is located before SCR system on exhaust pipe.

Error occurring Effect on the


Probable causes Remedial actions
condition vehicle
Error occurs if • Engine de- • NOx sensor 1. Check loose connection of sensor connector.
the NOx rates. Connector. 2. Connect Breakout harness & Box and
sensor1 CAN • NOx sensor. Check the continuity between ACM and EMS to
communication • Wiring harness. NOx sensor.
Pin1 & 2 signal 3. Check voltage b/w sensor connector pins to
lost ground.
4. Check resistance b/w sensor pins.
5. Remove EMS & ACM connectors and check
resistance b/w ECU pins.
6. Replace the sensor
7. If problems not solved then change EMS.
Connector view
ECU “B” connector Sensor connector

Circuit diagram

Circuit description:

From Pin No. To pin no Wiring Color Code Wiring Function


EB:36 1 0.5 L CAN4 High Signal
EB:35 2 0.5 G CAN4 Low Signal
Ground 3 0.75 BR Ground
ACM ECU 88 4 0.75 R/L Supply
Circuit Inspection

Pre- From pin


Type of inspection To pin no Expected result
condition no
1 EB:36
2 EB:35
Continuity Ignition Off Beep sound from Multimeter
3 Ground
4 ACM ECU 88
Sensor connector Pin 1 to 2 50 - 70 ohms
EB: 35 EB: 36 120 ohms
ACM:82 ACM:90 120 ohms
Resistance Ignition Off
Sensor Pin 1 to 4 110 ohms
Sensor Pin 3 to 4 450 ohms
Sensor Pin 2 to 3 250 ohms
1 Ground 2.0 – 4.0 V
Voltage Ignition On 2 Ground 1.0 – 3.0 V
4 Ground 24.0 V

Breakout Connection:-
Visual inspection (Electrical):

1. Check that the connectors are properly connected and locked into position
2. Disconnect and check the component connector
3. Inspect pins and terminals for oxidations or corrosion
4. Ensure that the pins and terminals are locked into the connectors and that they are not pushed
back out of the sockets
5. Check the pins and terminal are not damaged (which can cause poor connection)

Visual inspection (Mechanical):

1. Check sensor installation position


2. Check dust particles nearby sensor
3. Check proper torqueing of the sensor bolts.
4. Check AdBlue concentration in the fluid. Check Dosing valve & Pump unit.
5. Check the exhaust system.

Inspection using Fault code status check:

A) If there is a Short circuit DTC in the ECU, to identify whether the fault is in wiring harness or the
sensor, disconnect the component connector, (creating open circuit) and re-read fault code
status to see if status changes (where applicable).

o If the fault code changes i.e. open circuit DTC occurs, issue is with the internal circuit of
the component
o If the fault code does not change, issue is with the wiring harness

B) Connect a new sensor with the ECU and check whether the fault gets erased
o If the fault code gets erased, issue is with the internal circuit of the component
o If the fault code does not change, issue is with the wiring harness.

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