Lost Communication With NOx Sensor B

Where it lives

For U029E, the part to look at first is the sensor named here.

Check these first

• An open or short in the harness between the ECM and NOx sensor B
• A failed NOx sensor B
• An ECM fault blocking communication
• A damaged sensor harness
• Corrosion or water in the sensor circuit

What to do next

1. Inspect the wiring and connector at NOx sensor B
2. Monitor the NOx sensor B signal on a scan tool
3. Check the harness for damage or corrosion
4. Reflash or replace the ECM if the sensor tests good
5. Replace NOx sensor B if it does not respond
6. Clear the code and retest

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