Swirl flaps damaged or clogged
Often reportedSwirl flaps in the intake manifold can become clogged or break due to soot and carbon deposits, which may cause parts to enter the combustion chamber and damage the turbo and pistons.
Engine Internal
When buying a used BMW 1 Series 120d 2015 (F20 / F21), the most frequently mentioned issue is: Swirl flaps damaged or clogged. Also, Timing Chain Stretching/Breaking is commonly reported.
Engine varies by trim; verify the engine code on the listing.
Listed from most frequently reported, each with its source.
Swirl flaps in the intake manifold can become clogged or break due to soot and carbon deposits, which may cause parts to enter the combustion chamber and damage the turbo and pistons.
Engine Internal
The N47 2.0 diesel engine (184 HP) is known for early timing chain stretching and, in severe cases, breakage. This can cause metallic noises, vibrations, and loss of synchronization, potentially leading to serious engine damage.
Timing chain
In modern diesel engines of the 1 Series, the particulate filter (DPF/FAP) can clog quickly if the vehicle is mostly used in city or short-distance driving. Frequent incomplete regenerations cause dashboard warnings, increased fuel consumption, and in extreme cases, need for pressure cleaning.
Exhaust Emissions
The EGR valve in the N47 engine tends to clog with carbon deposits, causing idle fluctuation, power loss, increased fuel consumption and emissions, and difficulties with DPF regeneration. In some cases, recurring failures may require cleaning or replacement.
Exhaust Emissions
Same trim, different year
We only publish claims we can verify. Cards come from Difetti fault records matched to this vehicle on brand, fuel, engine and generation.