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U068E Lost Communication With EGR Temperature Sensor B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

GM documents this code in its 2025 diesel tables 25OBDG04A and 25OBDG04B, where sensor B is named EGR temperature sensor 1. Its circuit tests (P041C, P041D) are written for either a resistive probe or a digital thermocouple unit; the digital one counts as low below -72.8 °C. U068E covers the digital case: the check looks for SENT output switched off by an internal sensor fault, protocol errors or messages that are too old, and fails once 19 of 25 samples taken every 100 ms are bad while Run/Crank is active. It is Type A, so the MIL comes on in the first trip, and GM also logs a code for the input the sensor is wired to. Ford's 2023 diesels place sensor B behind the EGR cooler but read it as an analog signal. U068D, U068F and U0690 cover the other slots.

Likely causes

SENT signal, supply or ground wire to sensor B damaged
Internal fault in the sensor that shuts off its output
Connector corroded or contaminated by soot and oil
Fault at the controller input the sensor uses

Symptoms

  • Check engine light, on GM diesels in the first trip
  • Second code for the controller input stored alongside
  • EGR cooler efficiency not monitored

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–400
Time0.5–2 h

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

Parts involved

egr temp sensor bvehicle bus wiring

Related codes

U068DU068FU0690P041AP041BP041CP041DP041EP040F

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com.