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DTC codes / U01xx · Lost communication with a control module / U0169

U0169Lost Communication With Sunroof Control Module

U0169 is a generic communication fault indicating that the modules on the vehicle's Controller Area Network (CAN) bus have lost contact with the sunroof control module. The body control module or gateway typically sets this code after multiple failed attempts to receive status messages from the sunroof module, which may be due to a power, ground, or data bus issue rather than a failed module.

SystemNetwork
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaLost communication with a control module

Symptoms you may notice

  • The sunroof may not open, close, or tilt at all, or may move only in one direction.
  • The sunroof may operate intermittently or stop midway through its travel.
  • A sunroof or convenience feature warning light may illuminate on the dashboard.
  • Other body-related features such as interior lights or power windows may act erratically if the fault is shared with a common power or ground circuit.
  • Often no symptoms besides the warning light, especially if the sunroof was not recently used.

Common causes, most likely first

  1. Blown fuse or faulty relay supplying power to the sunroof control module.
  2. Corroded, loose, or damaged ground connection for the sunroof module.
  3. Open or shorted wire in the CAN bus or dedicated communication line between the sunroof module and the body control module.
  4. Water intrusion into the sunroof module connector or housing, causing corrosion or internal damage.
  5. Failed sunroof control module itself, though this is less common than wiring or power issues.
  6. Low battery voltage or a weak charging system causing modules to drop offline intermittently.

How to diagnose and fix it

  1. Verify battery voltage and charge the battery if it is below 12.4 volts, as low voltage can cause communication codes.
  2. Check the fuse and relay for the sunroof circuit, replacing any that are blown or suspect.
  3. Inspect the sunroof module connector for corrosion, water damage, or loose pins, and clean or repair as needed.
  4. Perform a voltage drop test on the power and ground circuits at the sunroof module to confirm they can carry current.
  5. Use a scan tool to check for communication with the sunroof module; if it does not respond, test the CAN bus wiring for opens or shorts.
  6. If wiring and power are good, substitute a known-good sunroof module or perform a relearn procedure if the module was replaced.
  7. Clear the code and verify the repair by operating the sunroof through several full cycles and confirming no code returns.

Common Misdiagnosis of U0169

  • A dead sunroof module is often blamed first, but a simple blown fuse or corroded ground is a far more frequent cause of this code.
  • Water leaks from clogged sunroof drains can soak the module and connector, so always check for dampness before replacing parts.
  • The code can set even if the sunroof works perfectly, because a single missed message on the CAN bus is enough to trigger it after a key cycle.
  • Other modules on the same bus, such as the door control module, can cause U0169 if they short the bus, so check for additional communication codes.
  • After replacing the sunroof module, some vehicles require a calibration or initialization procedure, and skipping it can leave the code stored.

Can I keep driving with U0169?

The vehicle remains safe to drive because the sunroof is a comfort feature and does not affect engine, steering, or braking. Avoid operating the sunroof until the fault is repaired, as it may move unexpectedly or fail in an open position during bad weather.

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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