What Does U029E Mean?
Communication failure between the control module and NOX Sensor B has occurred. This prevents proper monitoring of nitrogen oxide levels in the exhaust system for emission compliance.
Common Causes
40%
NOX Sensor B failure or internal sensor electronics malfunction
30%
Wiring harness damage or connector corrosion at Sensor B location
15%
Loss of power supply to NOX Sensor B
10%
Network communication circuit problem to Sensor B
5%
Sensor not calibrated or module software corruption
Diagnostic Steps
1
Step 1: Inspect NOX Sensor B mounting location for physical damage or exhaust leaks affecting sensor
2
Step 2: Test power and ground circuits at sensor connector per manufacturer specifications
3
Step 3: Check sensor heater element resistance and compare to specification
4
Step 4: Verify communication circuit continuity and proper voltage levels at sensor
5
Step 5: Replace sensor and perform initialization/relearn if circuits test within specification
Estimated Repair Cost
$400 - $1,200
Parts + labor, varies by vehicle and location
Communication failure between the control module and NOX Sensor B has occurred. This prevents proper monitoring of nitrogen oxide levels in the exhaust system for emission compliance.
The most common cause of U029E (Lost Communication With NOX Sensor "B") is: NOX Sensor B failure or internal sensor electronics malfunction
Typical repair costs for U029E range from $400 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but emissions system monitoring is disabled. May result in increased NOX emissions and emissions test failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U029E to identify the root cause.
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Quick Info
Category
Network
System
Emissions Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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