Damaged or corroded wiring harness at the EGR sensor D connector; Failed EGR sensor D itself, internally open or shorted; Poor ground connection shared by the EGR sensor and other modules; CAN bus wiring fault between the sensor and the module that monitors it; Water intrusion or oil contamination in the sensor connector; Loose or backed-out terminal pins in the sensor or module connector; Failed control module that is not transmitting or receiving on the network

DTC codes / U06xx · Network communication / U0669

U0669Lost Communication With EGR Sensor D

Q: What does code U0669 mean?

Lost Communication With EGR Sensor D. U0669 is a network communication code indicating that a control module on the vehicle's controller area network (CAN) bus has lost contact with the exhaust gas recirculation (EGR) sensor D, which is typically a position or differential pressure sensor integrated into the EGR system. The module that sets this code has stopped receiving regular status messages from that sensor over the communication bus, so it cannot verify EGR flow or position.

U0669 is a network communication code indicating that a control module on the vehicle's controller area network (CAN) bus has lost contact with the exhaust gas recirculation (EGR) sensor D, which is typically a position or differential pressure sensor integrated into the EGR system. The module that sets this code has stopped receiving regular status messages from that sensor over the communication bus, so it cannot verify EGR flow or position.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or stumbling when the EGR valve should be opening
Reduced engine performance or limp-home mode on some vehicles
Failed emissions test due to incomplete readiness monitors
Intermittent warning light that comes and goes with temperature or vibration
Other communication-related warning messages if multiple modules are affected

Common causes, most likely first

Damaged or corroded wiring harness at the EGR sensor D connector
Failed EGR sensor D itself, internally open or shorted
Poor ground connection shared by the EGR sensor and other modules
CAN bus wiring fault between the sensor and the module that monitors it
Water intrusion or oil contamination in the sensor connector
Loose or backed-out terminal pins in the sensor or module connector
Failed control module that is not transmitting or receiving on the network

How to diagnose and fix it

Inspect the EGR sensor D connector for corrosion, water, or loose pins and clean or repair as needed
Check the sensor's power, ground, and communication circuit voltages with a multimeter or oscilloscope
Perform a wiggle test on the harness while watching live sensor data to reveal intermittent faults
Verify the sensor's CAN bus messages are present using a scan tool with network diagnostics
Replace the EGR sensor D if it fails power, ground, or communication checks
Repair or replace damaged sections of the wiring harness between the sensor and the control module
Clear the code and perform a road test to confirm the communication fault does not return

Communication codes are not always sensor failures

A U0669 often sets because of a poor ground shared with other sensors, so cleaning ground points can fix it without replacing any parts.
The EGR sensor D may be a position sensor built into the valve assembly on some vehicles, making the whole valve the replacement item rather than a separate sensor.
Intermittent U0669 codes that appear only in wet weather usually point to water intrusion in a connector rather than a failed sensor.
A weak battery or charging system can cause multiple U-codes including U0669, so always check battery voltage and charging output first.
Scan tools that only read engine codes may not display U0669; a tool capable of reading all modules is needed to see network communication faults.

Can I keep driving with U0669?

The vehicle is generally safe to drive with U0669 because the fault affects emissions control rather than a safety system, but avoid long trips until diagnosed since a failed EGR sensor can increase emissions and may lead to limp mode. If the check engine light flashes or the engine runs poorly, stop driving and have it inspected promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.