"Is the 4 Serisi 420i reliable, and what should you check?"
When buying a used BMW 4 Series 420i 2014 (F32 / F33 / F36 / F82 / F83), the most frequently mentioned issue: ignition coils, injectors, and oil leaks affecting electronics. Also, lubrication problems, oil pump gear and seizure risk are commonly reported.
Engine: N20
N20B20B · 420i · Used in this car from 2013-2015
Strengths
Relatively low fuel consumption
Good potential for chip tuning
Watch-outs
Timing chain has low service life
Frequent leaks from under valve cover
Plastic pipes have short lifespan
Known engine issues
Timing chainThe most famous weak point of this engine is the modest service life of the timing chain, sometimes it lasts less than 80,000 km. Note that units after 2015 have a longer service life.
Oil pump chainAnother widespread problem of early engines was the breakage of the oil pump chain with fatal consequences. A new thicker chain appeared in September 2012.
Piston destructionN20B20A engines with compression ratio 10.0 are easily tuned and run without much trouble, but N20B20B engines with compression ratio 11.0 suffer from detonation after chip tuning.
Listed from most frequently reported, each with its source.
Ignition coils, injectors, and oil leaks affecting electronics
Often reported
On N20 engines, ignition coil and injector failures are reported; sometimes linked to oil leaks contaminating electrical components.
Engine Bay
Lubrication problems, oil pump gear and seizure risk
Often reported
Engine seizure and damage cases reported due to design-related (oil pump gear and related parts) and debris accumulation from worn components. In some instances, this has also led to turbo failure.
Engine Internal
Timing chain guide failure
Often reported
On the N20 2.0 engine, premature wear of timing chain guides is a documented issue and can lead to chain stretching or breakage.
Timing chain
BMW 4 Serisi 420i technical specs
BMW 4 Serisi 420i (2014): boot 445 L; fuel use 6,3 l/100 km (urban 8,6 l/100 km · extra-urban 5 l/100 km); 0–100 in 7.3 s.
Boot capacity
445 L
Fuel consumption
6,3 l/100 km (urban 8,6 l/100 km · extra-urban 5 l/100 km)
What should I look for when buying a BMW 4 Series 420i?+
When buying a 2014 model 420i, check the service history, test drive, and look for engine/transmission warnings. Most commonly reported issues: ignition coils, injectors, and oil leaks affecting electronics; lubrication problems, oil pump gear and seizure risk; timing chain guide failure.
What are the common problems of BMW 4 Series 420i?+
Most frequently reported issues: ignition coils, injectors, and oil leaks affecting electronics; lubrication problems, oil pump gear and seizure risk; timing chain guide failure.
Is the BMW 4 Series 420i reliable?+
Rather than a simple yes/no, it's best to weigh the proven pros and cons together. This page lists 3 verified findings.
How does Carbeak collect data?+
The cards on this page are derived from Difetti fault database records; the source vehicle is verified for brand, fuel, engine, and generation match with the target vehicle. Topics with insufficient evidence are not shown.