U1168 SCP Bus Communication Fault
The U1168 code indicates a failure in the SCP (Standard Corporate Protocol) J1850-based communication bus, specifically related to the primary data identifier. This Ford-proprietary protocol is used for module-to-module communication. The fault means a control module has not received or has received invalid data from the expected primary identifier, disrupting communication between systems like the PCM, BCM, or instrument cluster.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty control module that transmits the primary identifier
- Electrical interference or noise on the SCP (J1850) data bus
- Abnormal resistance in the SCP bus circuits (DLC pins 2 and 10)
- Loose connections or corrosion at data bus splice points
- Corrupt or outdated internal software in a control module
- Faulty instrument cluster (common on Ford platforms)
3. Symptoms You Will Notice
- Check Engine Light or other warning lights on
- Intermittent or complete loss of communication with modules (e.g., PCM, BCM, cluster)
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect DLC pins 2 and 10 for damage or corrosion
Check for loose or corroded connections at bus splice points
Measure resistance between DLC pins 2 and 10 (should be ~60 ohms)
Test for voltage and ground at each module on the SCP bus
If bus wiring and resistance are OK, suspect a faulty module or software issue
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may still be drivable, but communication issues can cause erratic behavior or loss of functions. It's best to diagnose and repair promptly to avoid further problems.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repairs range from $50 for a wiring fix to $500+ for module replacement or reprogramming.