Troubleshooting Mercedes-Benz Sunroof Problems

The most common problem with Mercedes-Benz sunroofs is a sunroof that doesn’t operate properly or barely moves. As you press the sunroof button, the sunroof only moves an inch or two at most when you try to open or close it. While this may seem frustrating and a headache, fixing this problem is usually very easy. Move the sunroof to the open position and then the closed position, which resets the sunroof and performs what is known as sunroof synchronization. The following video shows how to fix this very common issue with Mercedes-Benz and how to read/clear fault codes triggered by a defective sunroof from the Overhead Control Module.

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Synchronizing the sunroof on a Mercedes-Benz, for example, after disconnecting the battery, is a necessary and straightforward process that can typically be completed in just a few minutes. Simply keep the sunroof button pressed in the closed position. Then open the sunroof fully and keep the button open for five seconds to complete the calibration. After you follow these steps, the sunroof should be synchronized and operate correctly. If your Mercedes-Benz sunroof still has issues, resynchronizing it may not always be the solution. There are a few other issues that we discuss below.

Symptoms

While the sunroof synchronization issue is the most common problem with Mercedes-Benz, sunroofs can show other symptoms.

• Sunroof leaks – This can be caused by several issues, such as a clogged drain tube, a damaged seal, or a problem with the sunroof’s alignment. If the leak is severe, it can cause water damage to the interior of the vehicle.
• Sunroof gets stuck – This can happen if the sunroof becomes jammed due to a mechanical problem or a problem with the sunroof’s track.
• Sunroof won’t open or close – This can be caused by a problem with the sunroof’s motor or a problem with the electrical wiring.
• A sunroof makes noise – Sunroof can make noise when opening or closing; if a sunroof is making noise, it could be caused by a problem with the sunroof’s track or a problem with the sunroof’s motor.
• Sunroof not opening or closing fully – This can be caused by an issue with the sunroof’s track, a problem with the sunroof’s motor, or a problem with the sunroof’s control module.

Mercedes-Benz vehicles can start to have sunroof problems, especially as the vehicle ages or once it goes over 100,000.  Models such as the C300, C230, and even E350 are the models that we see experience the most issues with the sunroof. The older S500 and ML350 also tend to have issues with the sunroof, especially with clogged, drained lines. 

Common Mercedes-Benz Sunroof Problems 

If you’re experiencing any of these problems with your Mercedes-Benz’s sunroof, it’s best to have it inspected as soon as possible to avoid water getting inside the cabin and causing electrical issues and in some cases starting issues.

Leaking seals 

Every sunroof has rubber strips around it that seal it against the metal edges of the cars’ roofs. With time, they may become brittle, which causes them to develop cracks or even break apart. This reduces their ability to stop water from entering the cabin when it rains or while washing the car. The leak will initially be small but only worsen as time goes by. Rubber seals that lost their elasticity can sometimes be restored using specialized lubricants. But if they are cracked or broken, replacing them is the only reliable solution.

Clogged drains

A whole sunroof assembly has channels and tubes that remove any water that may get past its seals. However, leaves or dirt may clog these drain tubes, preventing water from passing. If that happens, any rain or liquid that may get inside the sunroof will stay there, with the resulting moisture causing mildew and unpleasant odors. The best way to unclog the drain tubes is by using hot water with detergent and an air compressor. 

Seized mechanism

The sunroof has several mechanisms that open it up or slide it backward. As with all other moving assemblies, these must be lubricated, with nothing obstructing their movement. But some owners are unaware of this, and the consequent lack of maintenance can take its toll. Insufficiently lubed mechanisms require more effort when moving, while seized ones may not even open. Still, a can of WD-40 and some silicone oil will solve the problem in most cases.

Electric motor

Most sunroofs have one or more electric motors that open them, which may fail for several reasons. An unlubricated or seized sunroof mechanism will add extra strain to the motor. If the friction between moving components is high enough, this can cause it to burn out. Additionally, electric motors may stop working if their internal moving parts wear out. For most models, the sunroof motor is available as a spare part. 

Overhead Control Panel module

Most newer Mercedes-Benz cars have a separate control module that operates the sunroof. Depending on the model, it is located either in the trunk or within the sunroof’s control panel. Despite being reliable, control modules can still cause issues in certain situations.

Use the YOUCANIC scanner to read the codes, clear them and look at live data from the sunroof module. Potential causes for malfunctioning include internal short circuits and corrosion caused by moisture.  Vehicles with panoramic sunroofs have a dedicated control module that typically is listed as PSD or Panormatic Sliding Roof.

Blown fuses 

As with any other electrical component, every sunroof has one or more fuses, which protect it from overloading situations. A fuse can blow, making everything in its circuit inoperable. So,  checking its fuses should be the first step if the sunroof suddenly stops working.

Panoramic Sunroofs

The most common problem with panoramic sunroofs is that they won’t open and get stuck when trying to open them due to a bad motor. When you try to press the open button, all you hear is noise. The shade for the panoramic sunroof can also get stuck due to the rails getting damaged, or the cloth may start to sag, but those are minor issues and easier to fix compared to a sunroof motor going bad.

Panoramic sunroofs are a great option, but if that sunroof starts to have problems, especially on a 10-year-old Mercedes, you may leave it as is because the repair costs can get too high.

What can I do to prevent sunroof issues? 

The sunroof is affected by weather and other unfavorable conditions that may impair its performance. But as one might expect, regular care and maintenance will do wonders in preventing this from causing more severe problems. 

• The roof’s rubber seals and metal edges should be washed thoroughly every few months. This will remove dirt buildups, which could otherwise cause wear and mechanical damage. In addition, applying a specialized lube to the seals will preserve them from deteriorating and breaking apart. 
• Flushing the drain tubes with warm water and solvent every once in a while will stop them from clogging up. This is much easier and faster than trying to remove hardened dirt buildups. How often this needs to be done depends on weather conditions and how dusty the ambient is. 
• The sunroof mechanism should be cleaned and lubricated once a year. This includes all moving parts and the tracks on which they slide. The easiest way is by using brake cleaner to dissolve any dirt buildups before applying a suitable lubricant. Among all the products on the market, dry silicon with Teflon is probably the best option. 

Troubleshooting

Sunroofs on most Mercedes-Benz cars are reliable and robust pieces of equipment. They have several potential failure points that can affect their performance. In most cases, worn seals and clogged drain tubes will cause leaks when it rains. Additionally, seized mechanisms or worn electric motors can stop the sunroof from moving. Lastly, sunroofs on many Mercedes-Benz models could fly away as they were not glued sufficiently, which resulted in a big recall. 

The YOUCANIC scanner can help you narrow down the issue with your Mercedes-Benz sunroof. Figuring out what may be causing your sunroof issue may not always be easy. This often results in false diagnoses, causing unnecessary repairs and unwanted expenses. If you’re experiencing any of these problems with your Mercedes-Benz sunroof, it may be best to have it inspected by a Mercedes-Benz technician.

Frequently Asked Questions