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420i / 430i (B48 / N20 2.0 turbo)

2013–2024 · petrol · 1998cc · 252hp

Engine codes: B48, N20

Maint. Sensitive

Reliability, common problems and owner reviews for the Bmw 4 Series 420i / 430i (B48 / N20 2.0 turbo). Check this before you buy used.

The 2.0 turbo petrols span the earlier N20 (F32) and the later modular B48 (F32 facelift/G22 — shared across the 3/5-Series and X-models). The B48 is the more robust, with a front-located timing chain (not the failure-prone N47-diesel rear); the older N20 was generally good but had earlier timing-chain-guide attention on some units — verify on cold start. Both carry the modern direct-injection cautions: intake-valve carbon over time, VANOS/PCV and turbo-coolant attention, and the ZF 8-speed auto (very robust) or DCT. A documented car with a healthy chain is dependable and quick. Buy on oil and (N20) chain history.

Same engine, other cars

This is the same physical engine (B48) sold under different names across brands. Reliability is broadly shared — cross-check these:

Known Issues

Timing chain (N20 early) / carbonrecurring

Some early N20 chain-guide attention (cold-start rattle); DI intake carbon on both.

Fix / Workaround: Check chain on N20 cold start; walnut-blast intake if rough.

Repair cost: €250–€1500

Typically appears after: 110,000 km

VANOS / PCV / turbo coolantrecurring

VANOS solenoids, PCV and turbo coolant lines with age.

Fix / Workaround: Clean oil; replace solenoids/lines as needed.

Repair cost: €150–€900

Typically appears after: 120,000 km

Year Cutoffs

2016: Before — . After — .

Mileage Thresholds

After 180,000 km: Carbon + (N20) chain window.

Pre-Purchase Checklist

  • ☐B48 is the more robust
  • ☐N20: cold-start chain check
  • ☐ZF 8-speed auto is excellent

Frequently asked questions

Is the Bmw 4 Series 420i / 430i (B48 / N20 2.0 turbo) reliable?

Maint. Sensitive — The 2.0 turbo petrols span the earlier N20 (F32) and the later modular B48 (F32 facelift/G22 — shared across the 3/5-Series and X-models). The B48 is the more robust, with a front-located timing chain (not the failure-prone N47-diesel rear); the older N20 was generally good but had earlier timing-chain-guide attention on some units — verify on cold start. Both carry the modern direct-injection cautions: intake-valve carbon over time, VANOS/PCV and turbo-coolant attention, and the ZF 8-speed auto (very robust) or DCT. A documented car with a healthy chain is dependable and quick. Buy on oil and (N20) chain history.

What are the common problems and reviews for the Bmw 4 Series 420i / 430i (B48 / N20 2.0 turbo)?

The most commonly reported problems: Timing chain (N20 early) / carbon, VANOS / PCV / turbo coolant.

Is a used Bmw 4 Series 420i / 430i (B48 / N20 2.0 turbo) worth buying?

Fine if serviced correctly — but it punishes neglect hard. History and the right consumables matter.