The UnderCover Flex tonneau cover is a popular choice for truck owners looking to protect their cargo and improve their vehicle’s appearance.
While many users are satisfied with their purchase, some have encountered issues.
In this article, I’ll walk you through the most common problems reported by UnderCover Flex owners and provide practical solutions.
Whether you’re a current owner or considering buying one, this guide will help you understand and address potential challenges.
Don’t worry – many of these issues have straightforward fixes!

UnderCover Flex Tonneau Cover: Common Problems and Solutions
Water Leakage Issues

One of the most frequently reported problems with the UnderCover Flex is water leakage.
This can be frustrating, especially if you’re relying on the cover to keep your cargo dry.
Common Causes of Leaks
Improper Installation
Sometimes, leaks occur because the cover wasn’t installed correctly. This could be due to misaligned rails or improperly tightened clamps.
Worn or Damaged Seals
Over time, the rubber seals that line the edges of the cover can wear down or become damaged, allowing water to seep in.
Clogged Drainage System
The cover has a built-in drainage system to channel water away. If this gets clogged with debris, water can back up and leak into the truck bed.
Solutions
Check and Adjust Installation
First, double-check that all components are properly aligned and tightened. Pay special attention to the rail clamps and make sure they’re at the correct height.
Inspect and Replace Seals
Carefully examine all the rubber seals for signs of wear or damage. If you find any issues, contact UnderCover for replacement parts.
Clean Drainage Channels
Regularly clean out the drainage channels to prevent clogs. A blast of compressed air can be effective for this.
Apply Additional Sealant
As a temporary fix, you can apply a weather-resistant sealant along the edges where leaks are occurring. However, this isn’t a permanent solution and you should address the root cause.
Quality Control Problems

Some users have reported receiving covers with manufacturing defects or missing parts. While this isn’t the norm, it can be a significant inconvenience.
Common Quality Issues
Missing Hardware
Some buyers have found that their cover arrived without all the necessary screws, clamps, or other small parts.
Misaligned Components
In some cases, parts of the cover may not fit together properly due to manufacturing errors.
Finish Imperfections
There have been reports of covers arriving with scratches, dents, or uneven paint.
Solutions
Immediate Inspection
As soon as you receive your cover, thoroughly inspect all components and compare them to the parts list in the manual.
Document Everything
Take photos of any defects or missing parts. This can be helpful if you need to file a warranty claim.
Latch and Closure Mechanism Failures

The latching system is crucial for keeping your cover secure, so problems in this area can be particularly frustrating.
Common Latch Issues
Misalignment
If the latch doesn’t line up properly with its catch, it may not close securely.
Broken Springs
The internal springs that help the latch snap into place can wear out or break over time.
Rust and Corrosion
In harsh environments, the metal components of the latch can rust, affecting its function.
Solutions
Adjust Latch Position
Most latches have some adjustability. Consult your manual for instructions on how to realign the latch.
Lubricate Moving Parts
Regularly applying a silicone-based lubricant can keep the latch mechanism working smoothly and help prevent rust.
Replace Worn Components
If adjustments and lubrication don’t solve the problem, you may need to replace the latch assembly. Contact UnderCover for the correct replacement part.
Weather Stripping and Seal Deterioration

The rubber seals around the edges of your cover play a crucial role in keeping water out. Over time, these can wear down or become damaged.
Signs of Seal Problems
Visible Cracks or Tears
Inspect the seals regularly for any visible damage.
Hardening or Brittleness
The rubber should remain flexible. If it feels hard or brittle, it’s likely degraded.
Gaps When Closed
If you can see light coming through when the cover is closed, the seals aren’t doing their job.
Solutions
Regular Cleaning and Conditioning
Clean the seals with a mild soap solution and apply a rubber conditioner to keep them flexible.
Temporary Fixes
For small gaps, you can use weather stripping tape as a temporary fix.
Replacement
If the seals are significantly damaged, you’ll need to replace them. Contact UnderCover for the correct parts for your model.
Mounting Rail Alignment Difficulties

Proper alignment of the mounting rails is crucial for the cover to function correctly and prevent leaks.
Common Alignment Issues
Uneven Installation
If the rails aren’t perfectly parallel, it can cause problems with the cover’s operation.
Interference with Bed Features
Some truck beds have features like tie-downs or utility tracks that can interfere with rail placement.
Warped Rails
In rare cases, the rails themselves might be warped or bent.
Solutions
Careful Measurement
Before installation, carefully measure and mark where the rails should go. Use a straight edge to ensure they’re perfectly parallel.
Adjustable Clamps
Most rail systems have adjustable clamps. Use these to fine-tune the rail position after initial installation.
Shims
If your truck bed isn’t perfectly flat, you may need to use shims to level out the rails.
Replacement Parts
If a rail is warped or damaged, contact UnderCover for a replacement.
Freezing and Operational Issues in Cold Weather

In colder climates, some users have reported problems with their covers freezing shut or becoming difficult to operate.
Cold Weather Challenges
Ice Formation
Water can freeze in the seals and joints, making it hard to open the cover.
Material Contraction
Extreme cold can cause the cover materials to contract slightly, affecting alignment.
Stiffening of Seals
Cold temperatures can make rubber seals less flexible, reducing their effectiveness.
Solutions
Regular Cleaning and Drying
Before freezing temperatures hit, make sure your cover is clean and as dry as possible.
Use a Lubricant
Apply a silicone-based lubricant to the seals and moving parts. This can help prevent ice formation.
Gentle De-icing
If your cover does freeze shut, use warm water to gently melt the ice. Avoid using sharp objects that could damage the seals.
Cover Storage
In extreme conditions, consider removing and storing the cover indoors when not in use.
Screws and Fasteners Coming Loose

Over time and with regular use, some owners have found that screws and other fasteners can work themselves loose.
Causes of Loose Fasteners
Vibration
The constant vibration from driving can gradually loosen screws.
Temperature Changes
Expansion and contraction due to temperature fluctuations can affect fastener tightness.
Improper Initial Installation
If fasteners weren’t properly tightened during installation, they’re more likely to come loose.
Solutions
Regular Inspections
Make it a habit to check all visible screws and fasteners periodically.
Use Thread Locker
When reinstalling screws, use a medium-strength thread locker to help keep them in place.
Proper Torque
When tightening fasteners, use a torque wrench to ensure they’re tightened to the correct specification.
Replacement
If you notice stripped or damaged screws, replace them immediately to prevent further issues.
Drainage System Inadequacies

While the UnderCover Flex includes a drainage system to channel water away, some users have found it insufficient in heavy rain.
Drainage Problems
Clogged Channels
Debris can accumulate in the drainage channels, preventing proper water flow.
Insufficient Capacity
In very heavy rain, the system may not be able to handle the volume of water.
Improper Routing
If the drain tubes aren’t properly routed, water can back up into the bed.
Solutions
Regular Cleaning
Periodically clean out the drainage channels and tubes. A pipe cleaner or compressed air can be helpful.
Additional Drainage
Consider adding extra drain holes in consultation with UnderCover support.
Proper Tube Routing
Ensure drain tubes are directed downward and away from the truck bed.
Sealant Application
As a last resort, you can apply additional sealant around problem areas, but be cautious not to block designed water flow paths.
Paint and Finish Quality Concerns

Some users have reported issues with the quality of the paint or finish on their UnderCover Flex.
Common Finish Issues
Scratches or Chips
The cover may arrive with minor scratches or chips in the paint.
Uneven Color
In some cases, the color may not perfectly match the truck’s paint.
Fading Over Time
Extended exposure to sunlight can cause the finish to fade.
Solutions
Immediate Inspection
Check the finish carefully upon arrival and report any issues to UnderCover immediately.
Touch-Up Paint
For minor scratches, use a matching touch-up paint to prevent rust and improve appearance.
Professional Refinishing
For more significant issues, consider having the cover professionally refinished.
Regular Cleaning and Waxing
To maintain the finish, clean the cover regularly and apply a high-quality automotive wax.
Incompatibility with Some Truck Bed Features

Depending on your truck model, you might encounter compatibility issues with certain bed features.
Potential Conflicts
Utility Track Systems
Some trucks have built-in track systems that can interfere with cover installation.
Bed Liners
Certain types of bed liners can make it difficult to properly install the rails.
Toolboxes or Other Accessories
Pre-existing accessories might need to be removed or relocated.
Solutions
Research Before Buying
Before purchasing, check UnderCover’s compatibility list for your specific truck model and year.
Custom Installation
In some cases, you may need to modify the installation process. Consult with UnderCover support for guidance.
Professional Installation
If you’re unsure about compatibility, consider having the cover professionally installed.
Accessory Adaptations
Look for tonneau cover-compatible versions of accessories you want to use with your cover.
Durability and Longevity Concerns

While the UnderCover Flex is designed to be durable, some users have reported concerns about its long-term durability.
Common Durability Issues
UV Damage
Extended sun exposure can degrade the cover material over time.
Stress Cracks
Repeated folding and unfolding can lead to stress cracks in some cases.
Hardware Wear
Hinges, latches, and other moving parts can wear out with frequent use.
Solutions
Regular Maintenance
Follow the manufacturer’s care instructions carefully, including cleaning and conditioning.
Protective Measures
When possible, park in shaded areas or use a truck cover to protect from UV damage.
Gentle Operation
Be careful when folding and unfolding the cover to minimize stress on the hinges and panels.
Timely Repairs
Address any small issues promptly to prevent them from becoming larger problems.
Warranty Coverage
Familiarize yourself with the warranty terms and don’t hesitate to use them if necessary.
Final Thoughts
While the UnderCover Flex tonneau cover has its share of potential issues, many of these problems can be prevented or easily addressed with proper care and maintenance.
By staying proactive and addressing small issues before they become big ones, you can ensure that your cover provides reliable service for years to come.
Remember, if you encounter any problems you can’t solve, don’t hesitate to reach out to UnderCover’s customer support for assistance.