Network, generic

U066A Lost Communication With EGR Sensor E

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

EGR sensors A to E are open slots in the code set: each maker decides whether a slot carries a valve position, a pressure or a differential pressure in the recirculation path. U066A means the engine controller no longer gets usable digital frames from the device it calls sensor E, typically a SENT part. No manufacturer documents this code publicly. In the published tables GM gives slot A to the high-pressure valve position and C to the low-pressure one, while Ford and GM use D for a SENT EGR pressure sensor (U0669); an E appears nowhere. CARB demands its own code when a digitally coded input goes silent. Analog faults of this slot are P2385 to P2389. Most systems then cut or limit EGR, and the EGR monitor stays incomplete.

Likely causes

Signal, supply or ground wire to EGR sensor E damaged by heat or chafing

Connector at the sensor loose, corroded or contaminated with soot

Sensor electronics no longer transmitting

Engine controller input or software fault

Symptoms

Check engine light
EGR switched off or limited, sometimes harsher combustion noise
EGR readiness monitor not complete

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–600

Time0.5–2.5 h

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

Parts involved

egr sensor evehicle bus wiring

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