Network, generic

U059F Invalid Data Received From NOx Sensor B

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Sensor B is normally the tailpipe NOx sensor behind the SCR catalyst, so its readings decide whether the catalyst efficiency test passes. The code means its CAN frames are present but unusable. GM's 2025 diesel tables run the same counter, protection value and checksum test as for sensor A, here on the post-catalyst signal set, and treat it as Type B. FCA lists it for Ram 3500 to 5500 Cab Chassis trucks with the 6.7 L Cummins: bulletin 18-012-13 (2012) and 18-042-20 (2014, calibration without ammonia delete) reflash the ECM because the light could come on with no hardware fault. U029E means the sensor is missing entirely, U05A2 that sensor B rejects engine data. A stored code blocks the SCR efficiency verdict, so check software before buying a sensor.

Likely causes

Engine controller calibration known to flag false faults (FCA reflash)
Control unit of the downstream NOx sensor damaged
Chafed wiring or water in the connector near the exhaust

Symptoms

  • Check engine light on
  • SCR efficiency monitor not completing
  • No noticeable change in power

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nox sensor b

Related codes

U029EU059EU05A8U05A2U030EP229E

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.