What Does U1138 Mean?
This code indicates that a control module is not receiving valid primary identification data over the SCP network. This typically involves module addressing or network arbitration issues where modules cannot properly identify themselves or other modules on the bus.
Common Causes
30%
Body Control Module addressing or initialization failure
25%
SCP network bus short circuit or termination failure
20%
Multiple modules with conflicting or duplicate addresses
15%
Corrupted module software or programming
10%
Aftermarket module installation causing network conflicts
Diagnostic Steps
1
Step 1: Scan all modules to identify which ones are present and communicating on network
2
Step 2: Check for recently replaced or added modules that may have addressing conflicts
3
Step 3: Measure SCP bus resistance with all modules connected (should be 100-120 ohms)
4
Step 4: Disconnect modules one at a time to isolate source of addressing conflict
5
Step 5: Verify module software versions and perform updates/reprogramming as needed
Estimated Repair Cost
$200 - $1,500
Parts + labor, varies by vehicle and location
This code indicates that a control module is not receiving valid primary identification data over the SCP network. This typically involves module addressing or network arbitration issues where modules cannot properly identify themselves or other modules on the bus.
The most common cause of U1138 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Body Control Module addressing or initialization failure
Typical repair costs for U1138 range from $200 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Multiple vehicle systems may malfunction unpredictably if modules cannot identify each other. Critical safety systems like ABS or airbags may be affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1138 to identify the root cause.
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Quick Info
Category
Network
System
Network Communication / Module Addressing
Difficulty
Type
Manufacturer
Recommended Tools
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