Ever glanced at your dashboard to see that dreaded “Blind Spot System Fault” message? You’re not getting the full safety benefit of your Ford’s technology when this happens. The Blind Spot Information System (BLIS) is designed to be your extra set of eyes, but when it fails, you’re back to relying solely on mirrors and over-the-shoulder checks. Let’s dive into what causes these failures and how you can get your system working properly again.
What Is Ford’s Blind Spot System?
Ford’s Blind Spot Information System uses radar sensors mounted behind your rear bumper to detect vehicles in adjacent lanes. When working correctly, it lights up indicators in your side mirrors when someone’s cruising in your blind spot. The same sensors power your Cross-Traffic Alert system, which warns you of approaching vehicles when backing out of parking spaces.
These features aren’t just conveniences—they’re critical safety tools that can prevent accidents. Unfortunately, many Ford models from 2017-2024 (including Explorers, Edges, F-150s, and Expeditions) commonly experience system failures.
Common BLIS Fault Warning Signs
Here’s what you might notice when your blind spot system isn’t working properly:
- Dashboard warning: “Blind Spot System Fault” or “Cross Traffic Alert Fault”
- Side mirror indicators that never light up (or stay permanently lit)
- System working intermittently, especially in wet conditions
- Warning messages that temporarily disappear after restarting your vehicle
- Multiple systems failing simultaneously (BLIS, windows, climate control)
One 2020 Ford Explorer owner reported recurring fault messages that would temporarily resolve after restarting but return whenever it rained—a common pattern suggesting a deeper issue.
Most Common Causes of BLIS System Faults
1. Water and Moisture Damage
Water is the number one enemy of your blind spot system. The radar sensors and their connections are vulnerable to moisture intrusion, especially during:
- Heavy rainstorms
- Car washes
- Driving through deep puddles
- High humidity conditions
A 2021 Ford Aviator owner discovered their BLIS faults consistently appeared after driving in wet conditions. Technicians found water had penetrated the sensor connectors, causing intermittent failures.
2. Sensor Disconnection and Physical Damage
Your BLIS sensors live a tough life behind your bumper, exposed to:
- Road debris impacts
- Bumper damage from minor collisions
- Vibration that loosens connections over time
- Corrosion from road salt and chemicals
In one case, a 2020 Ford Explorer’s fault was traced to a loose sensor connector that had worked its way free due to normal driving vibrations.
3. Software and Module Communication Failures
Modern vehicles are essentially computers on wheels, and software glitches happen:
- Module communication breakdowns between your BLIS and other vehicle systems
- Outdated firmware or failed updates
- Compatibility issues after dealer service
- Voltage fluctuations affecting module communication
A 2023 Ford Mustang Mach-E developed BLIS faults immediately after a door control module update, suggesting the new software interrupted proper communication with the blind spot sensors.
4. Wiring Harness Problems
The wiring connecting your BLIS components faces continuous stress:
- Frayed or broken wires from flexing and vibration
- Corrosion at connection points
- Short circuits from damaged insulation
- Voltage drops from aging electrical systems
A 2017 Ford F-150’s BLIS failure was traced to a broken wire in the left rear sensor harness, requiring specialized repair.
Finding the Problem: Diagnostic Steps
Check for Diagnostic Trouble Codes (DTCs)
The first step in fixing any BLIS fault is finding the specific error codes stored in your vehicle’s computer. Professional scan tools can retrieve these crucial codes:
- B13F3:97: Indicates radar sensor obstruction or corrosion
- U0233/U0232: Shows lost communication with obstacle detection modules
- B1445:11: Points to short circuits in related wiring
These codes provide the roadmap for repairs. For instance, a 2021 Ford F-150 with code B13F3 led technicians directly to a corroded sensor connector.
Visual Inspection of Sensors and Wiring
Sometimes the simplest approach works best. Look for:
- Damage to your rear bumper near sensor locations
- Dirt, mud, or debris covering sensor areas
- Water accumulation around sensor housings
- Visible wire damage or disconnected plugs
A thorough inspection might reveal problems like a 2016 Ford Escape’s corroded ground connection that was discovered behind the left fender, fixed by simply cleaning and applying dielectric grease.
Voltage and Circuit Testing
For more complex issues, testing electrical connections is essential:
- Battery voltage should be above 12.6V when the engine is off
- System voltage should maintain 13.5-14.5V with the engine running
- Sensor power supply should show consistent voltage
- Ground connections must show continuity and low resistance
A 2019 Ford Transit Custom owner found their intermittent BLIS faults correlated with low voltage readings, pointing to a failing battery management system rather than the BLIS itself.
DIY Solutions for BLIS System Faults
Before heading to the dealer, try these potential fixes:
Reset the BLIS System
Often, a simple reset can resolve software glitches:
- Turn off your vehicle completely
- Disconnect the negative battery terminal
- Wait at least 10 minutes (this allows capacitors to fully discharge)
- Reconnect the battery
- Start the vehicle and check if the warning has cleared
While not a permanent fix for hardware problems, this reset procedure resolves many temporary communication errors.
Clean Sensor Areas and Connections
Dirt and debris can block sensors or interfere with their operation:
- Locate the sensor areas (typically behind the rear bumper)
- Gently clean the visible portions with a damp cloth
- Remove any accumulated mud, snow, or road debris
- Spray electrical contact cleaner on accessible connections
- Apply dielectric grease to protect connections from future moisture
Several Ford owners report success after simply cleaning muddy sensor areas after off-road driving.
Check for Technical Service Bulletins (TSBs)
Ford has issued multiple bulletins addressing BLIS issues:
- TSB 21-2382: Addresses bracket replacements for 2020–2022 Escapes
- TSB 24-2028: Recommends shield installations for 2022–2024 Expeditions
- TSB 23-2266: Extends similar fixes to Navigators
These bulletins indicate Ford acknowledges design flaws in certain models. If your vehicle matches the description in a TSB, dealers may perform repairs at reduced or no cost, even outside warranty.
Professional Repair Options
When DIY approaches fail, professional solutions become necessary:
Dealer Diagnostics and Recalibration
Dealerships have specialized equipment to properly diagnose and repair BLIS issues:
- Ford-specific diagnostic tools to read proprietary codes
- Factory service information with model-specific repair procedures
- Capability to update module software to the latest version
- Proper targetting equipment for sensor recalibration
Ford’s TSB 23-2266 requires recalibrating radar sensors after bumper removal or software updates—a procedure requiring dealer equipment.
Sensor Replacement and Upgrades
When sensors fail, replacement may be the only option:
- Standard sensor replacement (part ML3Z-14C689-G)
- Upgraded bracket installation (LJ6Z-14D189-B/C) to resolve misalignment
- Sensor pigtail replacements (4U2Z-14S411-LC) for corroded connections
A 2020 Explorer owner reported complete resolution after a dealership replaced both sensors under warranty.
Protective Shield Installation
Ford has recognized the need for better environmental protection for radar sensors:
- Splash shields (NL1Z-9928370-AA) to prevent debris accumulation
- Improved sensor housing designs with better water resistance
- Upgraded seals and gaskets for connections
The official TSB 24-2028 outlines these shield installations as a permanent solution to recurring BLIS faults.
Comparison of BLIS Fault Repair Costs
Understanding potential repair costs helps you make informed decisions:
| Repair Type | DIY Cost | Professional Cost | Time Required |
|---|---|---|---|
| System Reset | $0 | $50-150 (diagnostic fee) | 15-30 minutes |
| Sensor Cleaning | $5-10 | $50-150 | 30-60 minutes |
| Wiring Repair | $20-50 | $200-400 | 1-3 hours |
| Sensor Replacement | $150-300 per sensor | $400-800 | 1-3 hours |
| Complete System Replacement | Not recommended | $800-1,500+ | 2-4 hours |
Warranty coverage significantly reduces these costs, making dealer diagnosis worthwhile for vehicles under 3 years/36,000 miles (or extended warranties).
Understanding Ford’s Technical Service Bulletins for BLIS
Ford has released several important bulletins addressing blind spot system issues:
TSB 21-2382: Radar Sensor Bracket Replacement
This bulletin specifically targets 2020–2022 Ford Escapes with misaligned sensors. The repair procedure involves:
- Removing the rear bumper fascia
- Replacing mounting brackets with improved versions
- Reinstalling and calibrating sensors
- Updating module software as needed
TSB 24-2028: Shield Installations
For 2022–2024 Expeditions experiencing random warnings, this TSB recommends:
- Installing protective shields to prevent debris accumulation
- Inspecting wiring for damage or corrosion
- Testing sensor functionality with specialized equipment
- Ensuring proper module communication
TSB 23-2266: Extended Coverage
This bulletin extends similar protections to Navigator models and additional Expedition years, acknowledging widespread issues with the system design.
These bulletins provide technicians with specific repair procedures and may offer coverage even for vehicles slightly outside their warranty period.
Real Owner Experiences with BLIS Faults
Learning from others’ experiences can help guide your repair approach:
Case Study: 2021 Ford Explorer in Wet Conditions
A Ford Explorer owner reported consistent BLIS warnings after car washes or rainstorms. After multiple dealer visits, technicians traced the issue to water ingress in the left sensor connector. The solution involved:
- Removing the rear bumper
- Replacing the damaged sensor connector
- Applying waterproof sealant during reinstallation
- Testing in controlled wet conditions
The repair eliminated the issue, even during heavy rainfall.
Case Study: 2023 Mustang Mach-E Software Issues
After a routine service update, a Mach-E owner experienced sudden BLIS failures. The dealer determined that a door module update had disrupted communication with the blind spot detection system. The fix required:
- Reflashing the Side Obstacle Detection Control Module (SODCM)
- Resetting the Body Control Module (BCM)
- Recalibrating the entire BLIS system
- Testing all related safety systems
This software-focused approach completely resolved the issue without hardware replacement.
The Bottom Line on Ford Blind Spot System Faults
The Ford Blind Spot Information System provides valuable safety benefits when working properly, but design limitations make it vulnerable to several common failures. Water intrusion, wiring problems, and software glitches account for most issues, with varying repair complexity and cost.
For vehicles under warranty, dealer service is the obvious choice. For older Fords, weighing repair costs against safety benefits becomes a personal decision. Thankfully, many issues can be resolved through relatively simple fixes like system resets, connector cleaning, or software updates.
By understanding your system’s weaknesses and addressing problems promptly, you can keep this important safety feature working properly throughout your vehicle’s life.
