What Does U1301 Mean?
The Class 2 serial data link has detected a short circuit condition affecting network communications. This is typically a different module or circuit segment reporting the same type of fault as U1300.
Common Causes
40%
Physical damage to Class 2 data bus wiring causing short to ground or B+ voltage
25%
Failed control module with internal short circuit on the Class 2 transceiver chip
20%
Improperly installed or incompatible aftermarket device connected to data bus
15%
Water intrusion or corrosion in module connectors causing cross-circuit contamination
Diagnostic Steps
1
Step 1: Check Class 2 data line voltage at diagnostic connector pin 2; should read 5-7V with normal pulsing signal
2
Step 2: Systematically disconnect control modules to isolate which module or circuit segment is causing the short
3
Step 3: Inspect harness routing and identify any areas where wiring may contact hot surfaces, sharp edges, or moving parts
4
Step 4: Test resistance to ground and B+ on Class 2 circuit with all modules disconnected (should be high resistance)
5
Step 5: Check for TSBs related to specific module failures or known wiring harness routing issues
Estimated Repair Cost
$150 - $950
Parts + labor, varies by vehicle and location
The Class 2 serial data link has detected a short circuit condition affecting network communications. This is typically a different module or circuit segment reporting the same type of fault as U1300.
The most common cause of U1301 (Class 2 Data Link Shorted) is: Physical damage to Class 2 data bus wiring causing short to ground or B+ voltage
Typical repair costs for U1301 range from $150 to $950, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Communication loss can affect critical safety systems such as ABS, traction control, and airbag operation. Vehicle functionality may be severely limited.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1301 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
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
