What Does U0073 Mean?
Communication bus A has lost power or is completely non-functional. No data transmission is occurring on this primary network.
Safety Warning
May cause complete vehicle shutdown or inability to start. Critical safety systems including ABS and airbags may not function.
Common Causes
35%
Blown fuse or open circuit interrupting power to bus A network
25%
Open circuit in bus A wiring harness due to broken wire
20%
Failed network gateway module disrupting bus A operation
15%
Corroded or disconnected ground connection for bus A circuit
5%
Complete module failure preventing network initialization
Diagnostic Steps
1
Step 1: Check all fuses related to communication bus A and network modules using fuse diagram
2
Step 2: Verify power and ground at gateway or master module for bus A circuit using multimeter
3
Step 3: Check for continuity along entire length of bus A positive and negative circuits
4
Step 4: Inspect all major connectors on bus A for disconnected or backed-out terminals
5
Step 5: Use scan tool to attempt communication with all modules, noting which modules are non-responsive
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
Communication bus A has lost power or is completely non-functional. No data transmission is occurring on this primary network.
The most common cause of U0073 (Control Module Communication Bus A Off) is: Blown fuse or open circuit interrupting power to bus A network
Typical repair costs for U0073 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause complete vehicle shutdown or inability to start. Critical safety systems including ABS and airbags may not function.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0073 to identify the root cause.
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Quick Info
Category
Network
System
Network Communication
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
