What Does U1100 Mean?
The control module has lost communication with another module on the SCP network and is not receiving its primary identification data. This is a general network communication fault indicating a module is offline or not responding.
Common Causes
35%
Failed control module no longer communicating on network
30%
Open or damaged network bus wiring preventing communication
20%
Poor power or ground connection to affected module
10%
Corroded or damaged module connector preventing network communication
5%
Aftermarket accessory interfering with network communication
Diagnostic Steps
1
Step 1: Identify which module is not communicating by checking all modules on scan tool for response
2
Step 2: Verify power and ground to the non-communicating module using a multimeter
3
Step 3: Inspect the non-responsive module's connector for corrosion, bent pins, or water damage
4
Step 4: Check continuity of network bus circuits from DLC to the affected module connector
5
Step 5: Test network bus voltage at multiple points; should see approximately 2.5V on both bus+ and bus- circuits
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
The control module has lost communication with another module on the SCP network and is not receiving its primary identification data. This is a general network communication fault indicating a module is offline or not responding.
The most common cause of U1100 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Failed control module no longer communicating on network
Typical repair costs for U1100 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Depending on which module has failed, critical systems like ABS, airbags, or engine control may be affected. Assess specific module function before determining drive-ability.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1100 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
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
