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DTC codes / U06xx · Network communication / U0690

U0690Lost Communication With EGR Temperature Sensor D

U0690 is a generic 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) temperature sensor D. The module monitoring the sensor expected regular data messages but stopped receiving them within the required time window, so it flagged the missing communication rather than a temperature value that is out of range.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illumination of the check engine light or a dedicated service warning on the dashboard.
  • Often no symptoms besides the warning light, because the fault is a communication loss rather than a failed sensor reading.
  • Possible rough running, hesitation, or reduced fuel economy if the EGR system defaults to a fixed strategy.
  • Intermittent warning light that comes and goes with vibration, moisture, or temperature changes.
  • Other unrelated warning lights or communication codes if the fault lies on a shared network segment.
  • A stored pending or history code that returns after clearing when the network fault is still present.

Common causes, most likely first

  1. Damaged, corroded, or loose wiring or connector pins at the EGR temperature sensor D or its harness.
  2. A failed EGR temperature sensor D that no longer transmits data on the network.
  3. A faulty or unpowered control module that is supposed to relay the sensor's messages.
  4. CAN bus wiring faults such as an open circuit, short to ground, or short to voltage on the data lines.
  5. Low battery voltage or a poor ground connection causing intermittent module communication dropouts.
  6. Aftermarket accessories or poor previous repairs that disturbed the network wiring.
  7. A software or configuration issue in a module that has not been properly initialized after service.

How to diagnose and fix it

  1. Scan all modules for stored and pending codes to identify which module reported U0690 and whether other network codes are present.
  2. Inspect the EGR temperature sensor D connector and harness for corrosion, loose pins, chafing, or moisture intrusion.
  3. Check battery voltage and the main grounds for the affected modules, since low voltage can mimic a network fault.
  4. Measure resistance and continuity on the CAN data lines at the sensor and at the module to rule out an open or short.
  5. If wiring and power are good, substitute a known-good EGR temperature sensor D and clear the code to see if communication returns.
  6. Verify the reporting module has the correct software and configuration, and reflash or relearn if required by the manufacturer.
  7. Clear all codes, perform a road test, and confirm the code does not return before releasing the vehicle.

Why U0690 is often a wiring fault

  • U0690 is a communication code, not a sensor performance code, so replacing the EGR temperature sensor D without checking the network wiring often fails to fix it.
  • A single chafed wire or corroded pin on the CAN bus can set U0690 alongside several unrelated communication codes, which is why a full module scan matters.
  • Intermittent U0690 codes frequently appear after battery replacement or jump-starting, when modules lose initialization or voltage spikes disturb the network.
  • Some vehicles report U0690 when a module is simply unplugged during service, so the code may be a history artifact rather than a live fault.
  • The code does not confirm the EGR temperature sensor D is faulty; it only confirms the monitoring module stopped hearing from it.

Can I keep driving with U0690?

The vehicle is usually safe to drive because the fault is a communication loss rather than a mechanical failure, but avoid long trips and heavy load until the cause is found. If the check engine light flashes or the engine runs poorly, stop driving and have the network fault diagnosed 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.

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