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U068D Lost Communication With EGR Temperature Sensor A

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

EGR temperature sensors show how hot the recirculated gas is, mostly behind the EGR cooler, so the controller can judge cooler efficiency and correct the gas density. U068D is the digital-link failure for sensor A. No public manufacturer source covers U068D. In the published tables sensor A is analog: GM's 2025 diesel table 25OBDG04A calls it the downstream EGR temperature sensor 2 and flags a resistance below 159 ohms as P040C, and Ford's 2023 diesel summary sets P040C under 0.69 V and P040B if the reading rises less than 10 °C after start. Neither has a SENT variant for A. CARB requires the EGR cooler to be checked and a separate code for any digital input that goes quiet. Analog faults are P040A to P040E; the A/B comparison is P040F.

Likely causes

Wiring to EGR temperature sensor A damaged near the cooler

Connector oily, sooty or corroded

Sensor electronics failed

Symptoms

Check engine light
EGR cooler monitoring not possible

Repair estimate

DifficultyMediumDIY possible

Parts and labour€50–350

Time0.5–2 h

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

Parts involved

egr temp sensor avehicle bus wiring

References: gsi.ext.gm.com, fordservicecontent.com, law.cornell.edu.