U1106 SCP Bus Communication Failure
The U1106 code indicates that a control module, typically the PCM, has detected a failed communication or invalid data on the SCP (Standard Corporate Protocol) J1850 bus, specifically related to legislated diagnostic information required for OBD-II emissions compliance. The SCP is a Ford-proprietary serial communication network operating at 41.6 kbps. This code sets when a module expects to receive emissions-related diagnostic data (such as monitor status, drive cycle counters, and test results) from another module on the bus, but the data is missing, corrupted, or does not meet OBD-II format requirements.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty control module that transmits legislated diagnostic data (PCM, TCM, or emissions module)
- Electrical interference or noise on the SCP (J1850) bus corrupting messages
- Abnormal resistance on the SCP bus lines (+ and/or -) due to poor connections, corrosion, or damaged wiring
- Faulty SCP bus terminator resistors (120 ohms at each end of the bus)
- Low battery voltage or charging system issues affecting module communication
- Outdated or corrupted control module software
- Incorrectly programmed or incompatible replacement control module
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test or readiness monitors not set
4. Step-by-Step Diagnosis
Scan for other related codes and check freeze frame data
Inspect battery voltage and charging system; ensure at least 12.6V
Visually inspect SCP bus wiring and connectors for damage, corrosion, or loose connections
Measure resistance between SCP bus (+) and (-) terminals at the DLC; should be approximately 60 ohms
Check for aftermarket accessories or modifications that may cause electrical noise
Verify module software updates and reprogram if necessary
Perform a network test to identify which module is not communicating
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive short distances, but it may fail an emissions test and the Check Engine Light will be on. Have it diagnosed soon to prevent potential drivability issues.
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.