2018 MINI Convertible Problems: 3 Issues Every Owner Should Know
2018 model year · 1,800+ owner reports · Updated April 2026
According to Au7o's analysis of 1,800+ owner reports, the 2018 MINI Convertible has 3 documented known issues. No issues are rated critical, indicating generally reliable ownership. The most commonly reported issue is Convertible Top Drain Tube Clogging and Water Leak with 1,800 owner reports. Across all issues, repair costs range from $0 to $1,500. DIY maintenance guides at au7o.io.
All 3 Known Issues
On the 2005-2025 MINI Convertible, the convertible top has drain tubes that channel water away from the folding mechanism. These tubes clog with debris, causing water to back up and leak into the cabin, trunk, or onto electrical components under the rear shelf.
Common Symptoms
- Water in trunk
- Wet carpet in rear footwell
- Musty smell
- Electrical malfunctions
- Water stains on headliner
How to Fix
Clear the drain tubes using compressed air or a flexible wire. There are 4 drain tubes total (2 front, 2 rear). This should be done at least once a year as preventive maintenance.
What Owners Are Using
Parts and tips from 1,800+ owners who fixed this issue
- Tip
- Tip
- UpgradeTrim removal tool set for body panel work without damage (MICTUNING Trim Removal Tool Set)
- UpgradeBondo body filler for dent and panel repair (Bondo Body Filler Kit)
On the 2005-2025 MINI Convertible, the MINI Convertible uses a hydraulic system to raise and lower the soft top. The hydraulic cylinders and lines develop leaks over time, causing the top to operate slowly, stop mid-cycle, or fail to latch securely. The hydraulic fluid (a specialized oil, not brake fluid) seeps from the cylinder seals and line connections. In colder climates, the seals harden and crack faster. The system operates at high pressure and even small leaks cause operational problems.
Common Symptoms
- Convertible top moves slowly or pauses during operation
- Top stops mid-cycle and will not complete opening or closing
- Hydraulic fluid visible on trunk lining or under rear seat
- Warning message indicating top malfunction
- Top does not latch securely when closed
How to Fix
Inspect all hydraulic lines and cylinder seals for weeping or fluid residue. Replace leaking hydraulic cylinders with OEM units. Top up the hydraulic fluid reservoir with the correct specification fluid (Pentosin CHF 11S or BMW-specified equivalent). Bleed the system after any line or cylinder replacement. The convertible top micro-switch alignment should also be checked, as a misaligned switch can cause the motor to over-pressurize the system.
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- Tip
- UpgradeDorman OE-replacement door latch assembly — direct fit (Dorman Door Latch Assembly)
- UpgradeDorman replacement door handle — matches OEM spec (Dorman Door Handle)
- UpgradeDorman weatherstrip seal prevents water leaks and wind noise (Dorman Weatherstrip Seal)
- Upgrade3M Super Weatherstrip Adhesive for reattaching loose seals (3M Weatherstrip Adhesive)
On the 2005-2025 MINI Convertible, the MINI Convertible has four drain tubes that channel water from the soft top well and seal channels to exit points under the car. These tubes are narrow and become clogged with leaves, debris, and algae over time. When clogged, water pools in the soft top storage well and overflows into the trunk, rear footwells, and can reach the body control modules located under the rear seats. Water damage to electronics can cause cascading electrical faults.
Common Symptoms
- Water pooling in trunk after rain or car wash
- Damp or wet carpet in rear footwells
- Musty or mildew smell inside car
- Intermittent electrical glitches (lights, windows, locks)
- Visible water stains in trunk or under rear seat
How to Fix
Clean all four drain tubes every 6 months using compressed air or flexible wire from the top opening. The drain exits are visible under the car near the rear wheels and rocker panels. Apply a thin film of silicone lubricant to keep the tubes clear. If water has already reached the interior, pull back the carpet, dry thoroughly, and inspect the wiring connectors under the rear seats for corrosion. Treat corroded connectors with electrical contact cleaner.
What Owners Are Using
Parts and tips from 0+ owners who fixed this issue
- Tip
- UpgradeDorman weatherstrip seal prevents water leaks and wind noise (Dorman Weatherstrip Seal)
- Upgrade3M Super Weatherstrip Adhesive for reattaching loose seals (3M Weatherstrip Adhesive)