What Does U1188 Mean?
This code indicates the control module is not receiving expected data from another module on the SCP (Standard Corporate Protocol) J1850 network bus. A specific module identified by its Primary ID is either not communicating or sending corrupted data.
Common Causes
35%
Failed or failing control module (powertrain, body, or instrument cluster)
30%
Corroded or damaged network bus connectors/terminals
25%
Open or short circuit in SCP bus wiring (pin 2 or pin 10 of DLC)
10%
Low vehicle battery voltage affecting module communication
Diagnostic Steps
1
Step 1: Check battery voltage - ensure 12.4V minimum with key off, 13.8-14.5V running
2
Step 2: Inspect all accessible network connectors for corrosion, damage, or poor connections
3
Step 3: Use scan tool to identify which module (by Primary ID) is not communicating on the SCP bus
4
Step 4: Check SCP bus voltage at DLC pin 2 - should see 5-7V fluctuating signal
5
Step 5: Test resistance across SCP bus - should measure approximately 60-120 ohms between pin 2 and pin 10
Estimated Repair Cost
$150 - $1,200
Parts + labor, varies by vehicle and location
This code indicates the control module is not receiving expected data from another module on the SCP (Standard Corporate Protocol) J1850 network bus. A specific module identified by its Primary ID is either not communicating or sending corrupted data.
The most common cause of U1188 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Failed or failing control module (powertrain, body, or instrument cluster)
Typical repair costs for U1188 range from $150 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience reduced functionality in multiple systems but is typically safe to drive. Loss of communication may affect safety features like ABS or airbag systems depending on which module is affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1188 to identify the root cause.
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Quick Info
Category
Network
System
Network Communication
Difficulty
Type
Manufacturer
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