The BMW 4 Series is the coupe, convertible and Gran Coupe version of the 3 Series — sharing its platform and engines. The F32/F33/F36 generation and the newer G22 are both on UK roads. As a newer model overall, fault rates are lower than on older BMWs but some issues are emerging.
Quick Facts — BMW 4 Series
Common Engines
420i, 428i, 430i, 440i, M4, 418d, 420d, 425d, 430d, 435d
6 Most Common BMW 4 Series Problems
These are the faults most frequently seen on the BMW 4 Series by UK garages — ranked by how commonly they occur and what they cost to fix.
Early F32 4 Series with the N47 diesel engine retain the timing chain risk. Check carefully on pre-2015 diesel 420d and 418d models.
💷 Typical repair cost: £2,000–£4,000+
Newer diesel 4 Series develop EGR and DPF issues. Short-journey use accelerates DPF blockage. DPF warning and limp mode are the symptoms.
💷 Typical repair cost: £200–£1,200
The F33 convertible folding roof can develop hydraulic leaks and mechanism faults. Slow operation or failure to open/close are the symptoms.
💷 Typical repair cost: £400–£1,500
Higher-mileage 4 Series with the N55 and B58 turbocharged petrol engines can develop valve cover gasket and turbo feed pipe oil leaks.
💷 Typical repair cost: £200–£600
The large iDrive touchscreen on newer 4 Series can develop pixel issues or go black. A common fault on older units.
💷 Typical repair cost: £300–£800
Individual LED elements within the adaptive headlights can fail, triggering a warning light and requiring headlight unit replacement — which is expensive.
💷 Typical repair cost: £500–£2,000
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BMW 4 Series — MOT Tips
Check N47 timing chain on early diesel models. DPF warning light is an automatic fail. Adaptive LED failures will trigger a warning light which is MOT-relevant. Verify convertible roof seals on F33.
Engine management light on before your MOT? It's an automatic fail. Run a
MotorLoom diagnostic for £1.99 to get the likely cause and repair cost before booking the test.
BMW 4 Series Tyres
Most BMW 4 Series models run 225/50 R17 or 245/40 R18 depending on trim level and year. Always check the placard inside the driver's door for the exact size for your vehicle.
Summary
The 4 Series is a stylish, well-built car. Pre-2015 diesel models carry the N47 timing chain risk. Later models are more reliable but EGR and DPF maintenance on diesels remains important.
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