BMW 4 Series: F33 Convertible retractable hardtop hydraulic and microswitch failure
F33 Convertible retractable hardtop hydraulic and microswitch failure is a common body & rust fault on the BMW 4 Series on the 2014–2020 cars, and we rate it major. Putting it right costs $900 to $4,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 20 documented faults on the BMW 4 Series.
- Vehicle
- BMW 4 Series
- Years
- 2014–2020
- System
- Body & Rust
What you are looking at
No photograph available
What goes wrong
The 4 Series Convertible uses a three-piece folding metal roof driven by a hydraulic pump, with microswitches telling the roof module where each panel and each latch is. Two things go wrong. The plastic hydraulic lines chafe and snap, dumping fluid into the boot and roof frame, and the microswitches in the front latch age and stop reporting, at which point the roof stops halfway and the car shows a roof-not-latched message. A roof stuck part open is not a car you can leave outside, and diagnosis is a specialist job because a failing switch often stores no fault at all. Switches are replaced in pairs, left and right together.
What you would notice
- Roof stops partway through opening or closing
- 'Convertible roof not latched' or similar message in the cluster
- Hydraulic pump whining on after the roof has stopped moving
- Oily residue in the boot corners, on the roof frame or on the parcel shelf
- Roof only operating on the second or third attempt
How to check it
Where to look. Hydraulic pump and reservoir behind the boot side trim, hydraulic cylinders in the roof frame and boot hinges, and microswitches in the front roof latches above the windscreen header rail.
Operate the roof fully open and fully closed at least three times before you talk about price — a roof that works once and then hesitates is the one that will strand you.
Watch and listen to the pump: it should run smoothly and stop cleanly at the end of each cycle, not keep running.
Shine your phone torch into the boot corners and along the roof frame and look for oily streaks or a hydraulic smell.
Check the boot floor and the carpet edges for damp, because a roof sitting slightly misaligned lets water past the seals.
Ask whether the roof has ever been repaired, whether the microswitches or hydraulic lines have been replaced, and get the invoice.
What it costs to put right
$900 to $4,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Has the roof ever stuck or needed more than one attempt to close?”
- “Have the microswitches or hydraulic lines been replaced?”
- “Has the roof mechanism ever been serviced or lubricated, and by whom?”
Now check the BMW 4 Series you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- HoodTech convertible roof specialists — 'BMW 4 Series 2014-2021 F33 Convertible Roof Faults & Car Hood Repairs'
- Cayman Autos — 'Specialist BMW 4 F33 Series Hard Top and Convertible Roof Repairs'
- BimmerForums.co.uk thread — '4 series F33 convertible roof not latched'
- BimmerFest thread — '4 series roof problem'
BMW 4 Series buyer questions
Is f33 convertible retractable hardtop hydraulic and microswitch failure serious on a BMW 4 Series?
We rate it major and common on the BMW 4 Series. The 4 Series Convertible uses a three-piece folding metal roof driven by a hydraulic pump, with microswitches telling the roof module where each panel and each latch is. Two things go wrong. The plastic hydraulic lines chafe and snap, dumping fluid into the boot and roof frame, and the microswitches in the front latch age and stop reporting, at which point the roof stops halfway and the car shows a roof-not-latched message. A roof stuck part open is not a car you can leave outside, and diagnosis is a specialist job because a failing switch often stores no fault at all. Switches are replaced in pairs, left and right together.
How much does it cost to fix on a BMW 4 Series?
$900 to $4,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which BMW 4 Series years are affected?
Our research records this fault on the 2014–2020 BMW 4 Series. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
Operate the roof fully open and fully closed at least three times before you talk about price — a roof that works once and then hesitates is the one that will strand you. Watch and listen to the pump: it should run smoothly and stop cleanly at the end of each cycle, not keep running. Shine your phone torch into the boot corners and along the roof frame and look for oily streaks or a hydraulic smell. Check the boot floor and the carpet edges for damp, because a roof sitting slightly misaligned lets water past the seals. Ask whether the roof has ever been repaired, whether the microswitches or hydraulic lines have been replaced, and get the invoice. Look here: Hydraulic pump and reservoir behind the boot side trim, hydraulic cylinders in the roof frame and boot hinges, and microswitches in the front roof latches above the windscreen header rail.