What Does U1612 Mean?
A module on the SCP network is not receiving acknowledgment responses when it broadcasts its primary identifier. This indicates a fundamental communication breakdown on the data bus network.
Common Causes
35%
Short circuit or open circuit in SCP data bus wiring (+ or - lines)
25%
Failed body control module or gateway module causing network disruption
20%
Corroded or damaged module connectors preventing proper communication
12%
Multiple module failures creating excessive network traffic or conflicts
8%
Aftermarket alarm or accessory interfering with network communication
Diagnostic Steps
1
Step 1: Measure resistance across SCP data bus lines (should be 60-120 ohms between + and - with all modules connected)
2
Step 2: Visually inspect all accessible SCP network wiring for pinches, cuts, or damage, especially near body flex points
3
Step 3: Disconnect modules one at a time while monitoring network to identify if a specific module is dragging down the bus
4
Step 4: Check for aftermarket devices spliced into network wiring and temporarily disconnect to test
5
Step 5: Use oscilloscope or network analyzer to check for proper voltage swing and signal quality on both SCP+ and SCP- lines
Estimated Repair Cost
$150 - $900
Parts + labor, varies by vehicle and location
A module on the SCP network is not receiving acknowledgment responses when it broadcasts its primary identifier. This indicates a fundamental communication breakdown on the data bus network.
The most common cause of U1612 (SCP (J1850) Lack of Acknowledgment for Primary Id) is: Short circuit or open circuit in SCP data bus wiring (+ or - lines)
Typical repair costs for U1612 range from $150 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause loss of various convenience and safety features. Warning lights and alerts may not function properly, masking other vehicle issues.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1612 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.
