Lost Communication with Sunroof Control Module
Diagnostic trouble code U0169 indicates that the vehicle's master control module (such as the BCM or gateway) has lost serial communication with the sunroof control module. This loss of communication prevents the exchange of data regarding sunroof operation commands, position, and diagnostics. The code sets when the supervising module does not receive expected messages within a specified time, which can result in partial or complete inoperability of the sunroof system.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Internal failure or lock-up of the sunroof control module (SCM)
- Open circuit, short to ground or power, or high resistance in the communication bus lines (CAN+/CAN-, LIN) to the sunroof module
- Loss of power supply or poor ground connection at the sunroof module
- Corroded, bent, disconnected, or water-damaged harness connector at the sunroof module
- Bus termination resistor out of specification (if the module incorporates one)
- Intermittent failure of the gateway or master network module (though this typically sets multiple communication codes)
3. Symptoms You Will Notice
- Sunroof does not operate or operates intermittently
- Sunroof position indicator or switch may not respond
4. Step-by-Step Diagnosis
Check for other communication-related DTCs to rule out a broader network issue
Inspect the sunroof module connector for corrosion, damage, or poor connection
Test power and ground circuits at the sunroof module
Check the communication bus (CAN/LIN) for shorts, opens, or high resistance
Verify bus termination resistance if applicable
Attempt to communicate with the sunroof module using a scan tool; if no response, suspect module failure
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive with this code, as it only affects the sunroof system. However, the sunroof may not operate or may be stuck in one position.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repair costs vary: a wiring fix may be $100-$300, while replacing a sunroof control module can range from $200 to $600 including parts and labor.