What Does U0051 Mean?
The negative (-) wire of communication bus C has an open circuit, meaning the electrical path is broken. This prevents any communication between modules on this network segment.
Common Causes
40%
Broken or severed CAN C- wire in harness
25%
Disconnected or loose connector on bus C circuit
20%
Corroded or pushed-back terminal pin losing contact
10%
Failed module with internal open circuit on CAN C- pin
5%
Damaged splice or junction point in bus C wiring
Diagnostic Steps
1
Step 1: Perform continuity test on CAN C- wire from end to end of the bus network
2
Step 2: Inspect all connectors on bus C for loose connections, backed-out pins, or corrosion
3
Step 3: Check splice points and junction blocks for broken connections or corrosion
4
Step 4: Disconnect modules sequentially and test continuity to isolate the open segment
5
Step 5: Verify terminating resistors are present and connected properly at network endpoints
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The negative (-) wire of communication bus C has an open circuit, meaning the electrical path is broken. This prevents any communication between modules on this network segment.
The most common cause of U0051 (Vehicle Communication Bus C (-) Open) is: Broken or severed CAN C- wire in harness
Typical repair costs for U0051 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Complete loss of communication on bus C may disable safety systems such as ABS, traction control, or advanced driver assistance features. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0051 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Communication Network
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
