What does code U029E mean?

Q: What does code U029E mean?

Lost Communication With NOx Sensor B. U029E means the engine control module (ECM) has lost the controller area network (CAN) communication signal from the nitrogen oxide (NOx) sensor designated as B, which is typically the downstream sensor after the selective catalytic reduction (SCR) catalyst. The ECM monitors the CAN bus for periodic messages from that sensor and sets this code when the expected messages stop arriving for a calibrated time.

DTC codes / U02xx · Lost communication with a control module / U029E

U029ELost Communication With NOx Sensor B

U029E means the engine control module (ECM) has lost the controller area network (CAN) communication signal from the nitrogen oxide (NOx) sensor designated as B, which is typically the downstream sensor after the selective catalytic reduction (SCR) catalyst. The ECM monitors the CAN bus for periodic messages from that sensor and sets this code when the expected messages stop arriving for a calibrated time.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.