What these engines share
The current-generation 2.0-litre premium diesels: Mercedes OM654 (2016–present, aluminium block, 1950cc) vs BMW B47 (2014–present, modular architecture). Both use SCR/AdBlue systems and represent the state of the art in diesel passenger car engines.
OM654 vs B47 at a glance
| OM654 | B47 | |
|---|---|---|
| Brand | Mercedes-Benz | BMW |
| Score | 76/100 | 80/100 |
| Verdict | ACCEPTABLE | BUY |
| Type | OM654 2.0 Diesel I4 | 2.0L Turbo Diesel I4 |
| Known issues | 6 | 5 |
OM654 — 76/100 (ACCEPTABLE)
Found in: A-Class, B-Class, C 220d, C 300d, C-Class, CLA, E 220d, E 220d Wagon
Key issues
- Roller rocker arm wear (engines built before mid-2018) — severity high, cost N/A, onset 95.000 km
- Timing chain stretch (chain at the gearbox end) — severity high, cost N/A, onset 120.000 km
- Crankshaft out of specification (recall, engines built July-December 2020) — severity minor, cost N/A, onset N/A
- Oil leak at the front crankshaft seal (vibration damper) — severity minor, cost N/A, onset N/A
B47 — 80/100 (BUY)
Found in: 1 Series, 2 Series, 2 Series Active Tourer, 218d, 3 Series, 320d, 320d GT, 4 Series
Key issues
- EGR cooler coolant leak — soot sludge, intake manifold melt, fire risk (recall) — severity critical, cost €820, onset N/A
- DPF blockage — city driving — severity high, cost €1.500, onset 50.000 km
- Timing chain (rear-mounted) — rare premature wear — severity minor, cost N/A, onset N/A
- Turbocharger failure — occasional — severity minor, cost N/A, onset N/A
Verdict: B47 wins by 4 points
The B47 scores 80/100 vs the OM654's 76/100 — a 4-point difference. A close call — both engines are in similar territory. Check the specific issues that matter to you.
Which one should you buy?
The B47 scores slightly higher, but neither is trouble-free. On an OM654 built before mid-2018, ask for proof the rocker arms were checked or replaced; on any OM654, listen for a timing-chain rattle after a cold start and confirm the coolant-pump recall was done. On a B47, confirm the EGR cooler recall was done and avoid a car that has lived on short city trips (DPF). The gap is small — pick by the car and its service history.
Generated from EngineScope's reliability database. Reviewed by the editorial team. Methodology →