What Does U1168 Mean?
The module monitoring this code is not receiving expected identification data over the SCP network from a primary control module. This indicates a communication breakdown with a critical module that should be constantly transmitting its presence on the network.
Common Causes
30%
Failed primary control module (PCM, BCM, or instrument cluster)
25%
SCP network bus wiring open circuit or short to ground
20%
Corroded or loose connector at primary module
15%
Power supply failure to primary module
10%
SCP bus termination resistor failure or improper termination
Diagnostic Steps
1
Step 1: Identify which primary module is referenced by checking manufacturer-specific documentation for your vehicle
2
Step 2: Verify power and ground at the suspected primary module using multimeter
3
Step 3: Use scan tool to attempt communication with the suspected module - check for response
4
Step 4: Measure SCP bus voltage at multiple points - should read approximately 2.5V at rest with activity during operation
5
Step 5: Check for TSBs related to module software updates or known network communication issues
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The module monitoring this code is not receiving expected identification data over the SCP network from a primary control module. This indicates a communication breakdown with a critical module that should be constantly transmitting its presence on the network.
The most common cause of U1168 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Failed primary control module (PCM, BCM, or instrument cluster)
Typical repair costs for U1168 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May affect critical vehicle functions depending on which primary module has failed. Vehicle may experience reduced functionality or enter limp mode.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1168 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Communication Network
Difficulty
Type
Manufacturer
Recommended Tools
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