What Does U0044 Mean?
The negative wire of communication bus B has voltage above specification or is shorted to power. This prevents proper network communication between modules.
Common Causes
35%
CAN bus B(-) wire shorted to voltage source or another powered circuit
30%
Faulty control module internally shorting bus line high
20%
Damaged wiring harness causing cross-circuit short
10%
Aftermarket accessory installation causing improper wiring connection
5%
Pinched or crushed harness at body seams or mounting points
Diagnostic Steps
1
Step 1: Measure voltage on CAN B(-) line with ignition on; should read approximately 2.5V, not battery voltage
2
Step 2: Check for short to power by measuring voltage with all modules disconnected
3
Step 3: Inspect wiring harness routing for pinch points, especially near body panels and hinges
4
Step 4: Disconnect modules systematically to identify which module is pulling bus high
5
Step 5: Repair wiring short or replace faulty module causing high voltage condition
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
The negative wire of communication bus B has voltage above specification or is shorted to power. This prevents proper network communication between modules.
The most common cause of U0044 (Vehicle Communication Bus B (-) High) is: CAN bus B(-) wire shorted to voltage source or another powered circuit
Typical repair costs for U0044 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Can disable multiple vehicle systems including powertrain, braking, and safety features. May result in no-start condition or unpredictable vehicle behavior.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0044 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
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.
