U1107 — SCP (J1850) Invalid or Missing Data for Legislated Diagnostics #

Note: The wording of this Diagnostic Trouble Code (DTC) may vary by vehicle manufacturer. Always check OEM service information for your specific model.

• U1107: SCP (J1850) Invalid or Missing Data for Legislated Diagnostics (Ford/Lincoln/Mercury)
• U1107: CAN Data Bus, No or Invalid Data Received for Emissions Diagnostics (Chrysler/Dodge/Jeep/RAM)
• U1107: Communication Error in OBD-II Diagnostic Circuit (General Motors/Chevrolet/Buick/GMC)

Code Overview for U1107 #

The U1107 DTC indicates that a vehicle’s onboard computer has detected invalid or missing data on the communication network that is critical for emissions-related diagnostics.
In most modern vehicles, multiple control modules—like the Engine Control Module (ECM), Transmission Control Module (TCM), and Body Control Module (BCM)—must share information across a digital network. The SCP (Standard Corporate Protocol), also known as J1850, is one such communication standard used primarily by Ford and some other manufacturers. When data crucial for legislated (government-mandated) diagnostics is not reliably exchanged, the U1107 code is triggered.
This can result from wiring faults, failed modules, or even brief network interruptions.
Addressing this code promptly is important, as it may impact emissions compliance and broader vehicle diagnostics.

Common Symptoms for Code U1107 #

Drivers may or may not notice immediate performance issues when U1107 is present, but the code often leads to secondary symptoms. These can range from subtle warning lights to loss of certain system functions. Typical signs include:

• Check Engine Light or Malfunction Indicator Lamp (MIL) illuminated
• Emissions test failure or readiness monitors not completing
• Communication-related warning lights (e.g., “No Bus” message)
• Intermittent or erratic gauge readings on the dashboard
• Loss of data display on scan tools or incomplete diagnostics
• Occasional rough running or performance dips (rare)

Most Likely Causes for U1107 #

The U1107 code typically results from interruptions or corruption in the vehicle’s communication network. Here are the most common causes, ranked by frequency:

1. Faulty or corroded wiring/connectors in the SCP/J1850 data lines
2. Loose or damaged ground connections affecting module communication
3. Malfunctioning control module (usually ECM, TCM, or BCM)
4. Aftermarket accessories interfering with network integrity
5. Low battery voltage or charging system problems

Step-by-Step Diagnostic for U1107 #

Proper diagnosis of U1107 requires a methodical approach, as network faults can be intermittent or hidden. Here’s a recommended step-by-step process:

• 1. Verify code presence and record freeze frame data with a professional-grade scan tool.
• 2. Inspect battery voltage and charging system for low voltage or fluctuations.
• 3. Visually inspect SCP/J1850 wiring harnesses and connectors for damage, corrosion, or loose pins—especially near modules.
• 4. Check ground connections at module mounting points. Clean and tighten as needed.
• 5. Disconnect aftermarket devices (alarms, stereos, remote starters) to rule out interference.
• 6. Perform module communication tests with a scan tool—identify which modules are not responding or reporting errors.
• 7. If isolated, swap suspect modules (if possible) with known-good units for confirmation.

Possible Repairs for U1107 #

Repairing a U1107 code always involves addressing the root cause to restore reliable data sharing between modules. Depending on your diagnosis, possible solutions include:

• Repair or replace damaged wiring or corroded connectors in the SCP/J1850 circuit
• Clean and secure all control module grounds
• Replace any faulty control module and perform required programming or configuration
• Remove or properly rewire aftermarket devices disrupting the network
• Recharge or replace the battery if voltage is low, and address charging system faults

Is It Safe to Drive with U1107? #

Limited. In many cases, you can drive with a U1107 code for short distances, as immediate engine or transmission damage is unlikely. However, because the code relates to legislated diagnostics, your vehicle may fail an emissions test or not display critical fault information. If you notice additional warning lights, erratic gauges, or performance issues, have the car serviced right away. Prolonged driving without repair may mask other serious faults.

Vehicles Most Commonly Affected by U1107 #

U1107 is most frequently reported on vehicles that use the SCP (J1850) communication protocol, particularly from the mid-1990s to late 2000s. Here are some examples:

• Ford F-150, Explorer, Taurus (1996–2006)
• Lincoln Town Car, Navigator (1998–2006)
• Mercury Grand Marquis, Sable (1998–2006)
• Chrysler PT Cruiser, Town & Country (2001–2007, with similar network)
• GM trucks/SUVs (1999–2005, J1850 variants)

Frequent Mistakes & Best Practices for U1107 #

Because network faults can seem random, technicians sometimes overlook basic causes or misdiagnose module failures. Avoid these pitfalls:

• Replacing expensive modules before checking wiring and grounds
• Ignoring battery and charging system health
• Overlooking recent aftermarket installations as possible sources of interference
• Not clearing codes after each step to verify the fix
• Using generic scan tools that can’t access all modules or proprietary networks

U1107 FAQ #

Even seasoned technicians have questions about communication codes like U1107. Here are quick answers to some common ones:

• Q: Will replacing the ECM always fix U1107?
  A: No. U1107 is often caused by simple wiring or power/ground issues. Only replace modules after thorough testing.
• Q: Can a weak battery trigger this code even if the car starts normally?
  A: Yes. Low voltage during startup or key cycles can disrupt network communication and cause U1107.