What Does U0023 Mean?
The positive (+) line of the low-speed CAN bus voltage is reading higher than specification. This typically indicates an open circuit on the CAN- line or an issue with bus termination.
Common Causes
30%
Open circuit in CAN- wire causing unbalanced bus voltage
25%
Failed termination resistor or improper termination
20%
Disconnected or loose connector on CAN network
15%
Damaged wiring harness with broken CAN- conductor
10%
Faulty module creating high impedance on CAN+ line
Diagnostic Steps
1
Step 1: Measure voltage on CAN+ line; voltage above 3.5V indicates high condition
2
Step 2: Check resistance between CAN+ and CAN- terminals (should be 60 ohms with modules connected, 120 ohms at each termination point)
3
Step 3: Verify all modules on low-speed CAN network are properly connected and powered
4
Step 4: Inspect wiring for breaks, particularly at flex points near doors and under seats
5
Step 5: Test termination resistors by measuring resistance at network endpoints with modules disconnected
Estimated Repair Cost
$150 - $750
Parts + labor, varies by vehicle and location
The positive (+) line of the low-speed CAN bus voltage is reading higher than specification. This typically indicates an open circuit on the CAN- line or an issue with bus termination.
The most common cause of U0023 (Low Speed CAN Communication Bus (+) High) is: Open circuit in CAN- wire causing unbalanced bus voltage
Typical repair costs for U0023 range from $150 to $750, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of communication may affect safety systems like airbag, ABS, or stability control depending on network architecture. Multiple warning lights may illuminate.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0023 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
Network Communications
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
