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U067E Lost Communication With Exhaust Pressure Control Valve B Sensor/Switch

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

An exhaust pressure control valve is a flap in the exhaust that diesels close partly to raise back pressure, which speeds warm-up and helps reach filter regeneration temperatures. Valve B is a second flap of this kind, and U067E concerns its position sensor or switch when that reports digitally: the controller has lost its messages. Public manufacturer documentation for U067E is lacking. GM's 2025 diesel table 25OBDG04B shows the pattern for valve A, a SENT position sensor whose silence gives U0650 after 480 failed checks out of 600 at 6.25 ms, Type A. For valve B, drive faults run from P049F to P04A5 and analog position faults from P04A6 to P04AA. CARB wants a separate code for a mute digital input. Warm-up and regeneration may be impaired.

Likely causes

Sensor wiring at valve B damaged by exhaust heat

Connector at valve B corroded or loose

Position sensor in the valve B unit failed

Engine controller input or software fault

Symptoms

Check engine light
Particulate filter regeneration delayed or not started
Longer warm-up in cold weather

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–800

Time0.5–3 h

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

Parts involved

exhaust pressure valve b sensorvehicle bus wiring

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