"Is the 4 Serisi 420d reliable, and what should you check?"
When buying a used BMW 4 Series 420d 2013 (F32 / F33 / F36 / F82 / F83), the most frequently mentioned issue is: Timing chain tension/failure (N47). Also, DPF clogging and difficult regenerations are commonly reported.
Engine: N47
N47D20C · 420d · Used in this car from 2013-2014
Strengths
Wide selection of versions and modifications
Economical for such power output
Watch-outs
Many problems with early diesel versions
Frequent oil leaks
Many versions have piezo injectors
Known engine issues
Timing chain driveEarly engines had low timing chain lifespan: guides wore out, chains stretched, and sharp teeth on the crankshaft sprocket accelerated the process. On updated N47TU or N47N engines, most weak points were eliminated.
Cracks in the blockThe aluminum block was initially designed without a special safety margin, and severe overheating could cause cracks between the second and third cylinders. With the update, the block was reinforced and such problems almost ceased.
Fuel systemAll engines in this series are equipped with a reliable Bosch Common Rail fuel system, but powerful versions with piezo injectors are quite demanding on fuel quality. Also, avoid driving with an empty tank, as the high-pressure pump may suck in air and start producing metal shavings.
Listed from most frequently reported, each with its source.
Timing chain tension/failure (N47)
Often reported
The 2.0 diesel engine in early versions (N47 family) is known for timing chain issues: premature loosening of the chain/tensioner assembly and, in extreme cases, breakage leading to engine damage.
Timing chain
DPF clogging and difficult regenerations
Often reported
The diesel particulate filter (DPF) in the 420d can clog, especially with city or short-distance driving, leading to warning lights and reduced performance.
Exhaust Emissions
EGR valve and EGR cooler clogging and damage
Often reported
On 2.0 diesel versions, issues with the EGR valve and in some cases the EGR cooler (cracks or leaks) are reported. The fault manifests as increased black smoke, power loss, and more difficult DPF regenerations.
Exhaust Emissions
BMW 4 Serisi 420d technical specs
BMW 4 Serisi 420d (2013): fuel use 4,7 l/100 km (urban 5,8 l/100 km · extra-urban 4,1 l/100 km); 0–100 in 7.5 s.
Fuel consumption
4,7 l/100 km (urban 5,8 l/100 km · extra-urban 4,1 l/100 km)
What should I look for when buying a BMW 4 Series 420d?+
When buying a 2013 420d, check service history, test drive, and engine/transmission warnings. Most commonly reported issues: Timing chain tension/failure (N47); DPF clogging and difficult regenerations; EGR valve and EGR cooler clogging and damage.
What are the chronic problems of the BMW 4 Series 420d?+
Most commonly reported issues: Timing chain tension/failure (N47); DPF clogging and difficult regenerations; EGR valve and EGR cooler clogging and damage.
Is the BMW 4 Series 420d 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 and target vehicle are verified for brand, fuel, engine, and generation compatibility. Topics with insufficient evidence are not shown.