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DTC codes / U06xx · Network communication / U067C

U067CLost Communication With Fan 3

U067C is a network communication code indicating that a control module on the vehicle's Controller Area Network (CAN) bus has stopped receiving messages from the fan control module responsible for Fan 3. The module that sets this code has detected a loss of expected periodic communication from the Fan 3 controller, which typically manages an auxiliary or condenser cooling fan on vehicles with multiple fan assemblies.

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

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) or a message on the driver information center
  • One or more cooling fans failing to run, which may lead to higher engine or air conditioning condenser temperatures
  • Air conditioning performance may degrade because the condenser fan does not activate when demanded
  • Engine coolant temperature may rise above normal in traffic or during extended idle periods
  • Often no symptoms besides the warning light, especially if the vehicle has enough airflow at speed to keep temperatures in check

Common causes, most likely first

  1. A failed fan control module or the fan assembly that houses the Fan 3 controller
  2. Damaged, corroded, or disconnected wiring or connector pins in the Fan 3 module circuit
  3. A blown fuse or poor ground connection supplying power to the Fan 3 control module
  4. CAN bus wiring faults such as an open circuit, short to ground, or short to voltage on the communication lines
  5. A faulty or unresponsive control module on the network that is disrupting communication
  6. Low battery voltage or a charging system issue causing modules to drop offline intermittently
  7. Water intrusion or corrosion inside the fan module connector or module housing

How to diagnose and fix it

  1. Verify the stored code and check for any related communication or fan circuit codes using a scan tool that can access all modules
  2. Inspect the Fan 3 module connector and wiring for corrosion, loose pins, or physical damage, and repair as needed
  3. Check the fuse and ground connections that feed the Fan 3 control module and restore power or ground if faulty
  4. Measure CAN bus voltage and resistance at the Fan 3 module connector to confirm the communication lines are intact
  5. Perform a bidirectional fan activation test with the scan tool to see whether the module responds to commands
  6. Substitute a known-good fan module or fan assembly only after circuit and power checks pass, then clear codes and retest
  7. If communication returns but the code resets, check for intermittent faults by wiggle-testing harnesses while monitoring live data

Why Fan 3 Communication Codes Mislead

  • A missing fan module often does not disable the primary cooling fan, so the engine may not overheat immediately and the fault can go unnoticed until the air conditioning suffers.
  • Technicians frequently replace the fan assembly when the real problem is a chafed CAN wire near the radiator support or a corroded ground that only fails under vibration.
  • This code can be set by a low or failing battery because modules that briefly drop offline during cranking may not re-establish communication cleanly.
  • Some vehicles use a single fan module to control multiple fans, so a U067C may actually point to a shared module fault rather than a dedicated Fan 3 component.
  • Aftermarket accessories wired into the fan circuit or CAN bus can introduce noise or voltage drops that mimic a failed Fan 3 module.

Can I keep driving with U067C?

The vehicle is generally safe to drive short distances, but avoid heavy traffic, long idles, and demanding air conditioning use until the fault is repaired because the loss of Fan 3 can cause overheating or poor A/C performance. If the temperature gauge climbs above normal, stop driving and let the engine cool.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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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