U066A

Code

Generic U — Network/User

Lost Communication With EGR Sensor E

Brand: Generic

Type: U — Network/User

Views: UK: 18 EN: 32 RU: 18

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Page language: EN

Open or short in EGR Sensor E communication wiring (CAN/LIN or dedicated signal wire)
Corroded, loose, or damaged connector at the EGR sensor or module
EGR Sensor E power supply or ground missing or intermittent
Failed EGR Sensor E (internal electronics)
Faulty or unpowered ECU/module that should transmit or receive the sensor message
Bus wiring fault: CAN/LIN short to battery/ground, missing termination, or high resistance

Read freeze frame and full DTC list; note occurrence count and other U- or P-codes
Use a capable scan tool to view live data — verify absence of EGR Sensor E parameters and check message frequency
Check for other network communication errors on CAN/LIN (U-codes)
Visually inspect EGR Sensor E connector, pins, and wiring for corrosion, damage, pin push-out, or water
Verify sensor supply and ground at the connector with key on (backprobe): expected reference (5V or 12V) and good ground
Measure CAN_H and CAN_L idle voltages (approx. 2.5V each) and differential with an oscilloscope or multimeter; check for proper 60 ohm termination across CANH-CANL

CAN bus idle: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V, differential ≈ 0 V (subject to measurement method); expected differential swing during traffic
CAN bus termination: ≈ 60 ohm between CAN_H and CAN_L (two 120 ohm in parallel)
EGR sensor supply: commonly 5 V reference or battery (12 V) depending on sensor type — verify OEM spec
Signal line expected to carry periodic message/frame (EGR data) at regular interval (e.g., 10–200 ms) — verify presence with scan tool or scope
Sensor signal voltage range (if analog): often 0–5 V corresponding to position/value — verify against OEM spec

Confirm the U066A code, record freeze frame and any simultaneous codes. Clear codes and see if U066A returns immediately or after drive. 2) Use scan tool to confirm EGR Sensor E data is absent and check other modules for the same missing data. 3) Inspect the EGR sensor connector and wiring for damage, corrosion, or water ingress; repair as needed. 4) Backprobe the sensor connector with key on: verify sensor supply voltage and ground presence per OEM specification. 5) Check communication bus health: measure CAN_H/CAN_L voltages and resistance between them (≈60 ohm). Use an oscilloscope to look for valid CAN traffic and for the EGR message if available. 6) If bus topology or traffic is suspect, isolate sections of the bus (disconnect suspected nodes) to find a short or noisy device. 7) Perform continuity checks from sensor communication pin to the receiving module pin with ignition off; repair any open/short. 8) If wiring and power/ground are good but no messages appear, swap or bench-test the EGR sensor (if possible) or replace with a known-good sensor. 9) If replacement sensor does not restore communication, inspect/replace or reflash the receiving module/ECU as required and verify software/calibration levels. 10) After repairs, clear DTCs, verify live data presence, perform road test and confirm code does not return.