When buying a used BMW 4 Series 420d 2015 (F32 / F33 / F36 / F82 / F83), the most frequently mentioned issue is carbon buildup in the EGR and intake ports. Timing chain stretching/wear (rarely reported) is also commonly noted.
Engine varies by trim; verify the engine code on the listing.
Listed from most frequently reported, each with its source.
On 2.0 diesel units (B47 family), carbon deposits are reported in the EGR valve, EGR cooler, and intake ports; this can cause idle fluctuations, lack of response, exhaust smoke, and occasional check engine light.
Engine Internal
The BMW 2.0 diesel engine family (especially the earlier N47) has a known history of timing chain stretching or premature wear. Although the B47 was designed to improve this, isolated reports exist.
Timing chain
On modern BMW 2.0 diesel engines, especially with city or short-distance driving, incomplete DPF regenerations and clogging issues can occur.
Exhaust Emissions
In some 2.0 diesel examples, issues with the common rail system (injectors or high-pressure pump) are reported, causing power loss, uneven distribution, smoke, and check engine light.
Fuel System
Turbocharger failures or wear are reported on the 2.0 diesel: wastegate actuator issues, loss of boost pressure, or abnormal noises. Common causes include deposit buildup, hard driving, or inadequate maintenance.
Turbo
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.