U0518: Door Switch C Data Fault
Diagnostic trouble code U0518 indicates that the vehicle's control module has received invalid or erroneous data from the module or switch identified as 'Door Switch C'. This is detected over the vehicle's communication network (CAN or LIN bus), where a receiving module identifies inconsistencies in the data frame, out-of-range values, or incorrect checksums from that switch. Per SAE J2012, U0xxx and U1xxx codes are generic network communication codes, though the specific subcomponent designation may vary by manufacturer.
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 of the Door Switch C
- Short circuit, open circuit, or high resistance in the communication wiring between the switch and the control module
- Poor connection or corroded terminals at the door switch connector
- Lack of voltage supply or ground to the Door Switch C
- Failure in the main control module receiving the signal (e.g., Body Control Module)
- Electromagnetic interference (EMI) on the data line
3. Symptoms You Will Notice
- Door-related functions (e.g., lock, window, or courtesy light) may be inoperative or erratic
- Check Engine Light or other warning lights may illuminate
4. Step-by-Step Diagnosis
Scan for additional related codes and note freeze frame data
Visually inspect the Door Switch C connector and wiring for damage, corrosion, or loose connections
Test voltage and ground at the switch connector
Check communication bus wiring for shorts, opens, or high resistance
If wiring is okay, test the switch itself for proper operation
If switch tests good, suspect a fault in the receiving control module (e.g., BCM)
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive as this is a low-severity code. However, some door-related features may not work properly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the issue is a simple wiring repair or requires replacing the door switch or control module.