Most of Europe's used diesels are imported from Germany and the Netherlands, and reliability swings wildly between generations of the same engine family. A Volkswagen TDI can be a million-kilometre legend or a money pit depending on which one you buy. This guide ranks the diesels worth owning — and flags the ones that will empty your wallet — using EngineScope's reliability scores, the models each engine powers, documented failure modes, and real repair costs.
Every score below comes from the engine's documented issues, repair-cost data, and failure patterns. Click any engine for its full report.
The most reliable diesel engines
| Rank | Engine | Brand | Score | Verdict |
|---|---|---|---|---|
| 1 | OM612 | Mercedes-Benz | 92/100 | BEST |
| 2 | 1.9 TDI (ALH/AHF/ASV) | Volkswagen | 89/100 | BEST |
| 3 | N16A 1.6 i-DTEC | Honda | 85/100 | BEST |
| 4 | 4.0 TDI V8 EA898 | Audi | 84/100 | BUY |
| 5 | 1.8 TDDi / DI (Endura-DI) | Ford | 84/100 | BUY |
| 6 | 1.1 CRDi (D3FA) | Hyundai/Kia | 84/100 | BUY |
| 7 | TD4 (M47) | Land Rover | 84/100 | BUY |
| 8 | OM606 | Mercedes-Benz | 84/100 | BUY |
| 9 | OM648 | Mercedes-Benz | 84/100 | BUY |
| 10 | B57 | BMW | 82/100 | BUY |
| 11 | 1.6 CRDi (D4FB) | Hyundai/Kia | 82/100 | BUY |
| 12 | OM656 | Mercedes-Benz | 82/100 | BUY |
| 13 | 2GD-FTV | Toyota | 82/100 | BUY |
| 14 | 1.7 Blue dCi (R9N) | Renault | 82/100 | BUY |
See the full list on the Best Diesel Engines page.
The legends
OM612 (Mercedes-Benz) — 92/100 → The highest-scoring diesel we track. Mercedes' smooth 2.7 five-cylinder common-rail engine (1999–2006); its one known weak point is the injector copper seals ("black death") — cheap if caught early, expensive once the injectors seize. Found in: Mercedes-Benz C 270 CDI (W203), E 270 CDI (W210).
OM606 (Mercedes-Benz) — 84/100 → The benchmark of the old school. Mercedes' 3.0 inline-six diesel from the 1990s is mechanical, over-built, and routinely passes 500,000 km. Its fault list is only age-related trivia; the 84 reflects how few independent sources document it. Found in: Mercedes-Benz 300D, E 300D (W124 / W210).
OM648 (Mercedes-Benz) — 84/100 → Mercedes' refined straight-six common-rail diesel (E 320 CDI era), successor to the OM613. Found in: Mercedes-Benz E-Class (W211 E 320 CDI), S-Class (W220 S 320 CDI).
1.9 TDI ALH/AHF/ASV (Volkswagen) — 89/100 → The people's million-kilometre engine. Simple distributor-pump design, no DPF, no timing chain to fail — the single most reliable diesel in the mainstream used market. Found in: VW Golf, Passat, Polo, Touran; Audi A3, A4, A6; SEAT Ibiza, Leon, Alhambra; Škoda Octavia, Fabia, Superb.
Safe modern buys
If you want something from the last 15 years rather than a classic, these earned a BUY verdict:
- Renault 1.5 dCi K9K (2010 on) — 78/100 → — Europe's most common small diesel, in its Euro 5/6 form: the swarf-shedding Delphi pump of the early engines is gone, bearing wear is rarer but not eliminated, and the DPF needs regular motorway runs. The pre-2010 K9K is a different proposition (62/100 CAUTION — con-rod bearings and Delphi pumps). In: Renault Clio, Megane, Captur, Kadjar, Scenic; Dacia Duster, Sandero, Logan; Nissan Qashqai, Juke, Micra, X-Trail.
- Hyundai/Kia 1.6 CRDi D4FB — 82/100 → — the dependable Korean diesel; watch DPF health on city cars. In: Hyundai i20, i30, Tucson, Santa Fe, Kona; Kia Ceed, Sportage, Rio, Soul.
- Toyota 1GD-FTV — 80/100 → — tough 2.8 diesel, but 2015–2020 builds had a DPF defect that an Australian court ruled made the cars "not of acceptable quality"; check the 2020 DPF fix was fitted. In: Toyota Hilux, Land Cruiser.
- BMW B47 — 80/100 → — the engine that replaced the troubled N47; its chain is no longer a weak point, but check the EGR-cooler fire recall was done. In: BMW 1, 2, 3, 4, 5 Series, X1, X3, X5.
- BMW M57 — 78/100 → — the good BMW diesel six, before the N47's chain problems; on cars built to about 2004, check the early metal swirl flaps were blanked. In: 3, 5, 7 Series, X5.
Why the VW 2.0 TDI is no longer on this list: the common-rail 2.0 TDI is two engines. The EA189 (2007–2015) scores 62/100 CAUTION — the Dieselgate recall must be done and its Bosch CP4.1 high-pressure pump can fail — and the EA288 (2012 on) scores 69/100 ACCEPTABLE, with cooling and emissions hardware (early water pump, EGR cooler, intercooler, AdBlue) as its weak points. See EA189 vs EA288.
Diesels to avoid or approach with caution
These have documented, expensive failure modes. Walk away — or negotiate hard.
- JLR Ingenium 2.0D pre-2019 — 48/100 → — early engines are known for timing-chain stretch that can destroy the engine, balance-shaft bearing wear and turbo failures; JLR revised the chain and bearings for model year 2020. Buy only with a full, short-interval service history. In: Jaguar XE, XF; Land Rover Discovery Sport, Range Rover Evoque.
- BMW N47 — 54/100 → — the infamous rear-mounted timing chain. If it snaps it usually destroys the engine, and a preventive chain job runs €1,500–4,000 because the gearbox must come out to reach it. Later engines are also in BMW's EGR-cooler fire recall, and EGR and DPF problems pile on. In: BMW 1, 3, 5 Series, X1, X3; MINI Cooper, Countryman, Clubman.
- Mercedes OM651 (early) — 66/100 → — timing-chain wear from about 150,000 km, plus piezo injectors (€1,400–2,000) on the 220 CDI to 2010/11 and every 250 CDI; the later OM651 (72/100) and the OM654 are safer. In: Mercedes C-Class, E-Class, GLK.
- Mercedes OM642 — 65/100 → — the 3.0 V6 diesel across the Mercedes range: main-bearing failures on early engines, leaking valley oil-cooler seals (up to €2,000) and swirl-flap failures (€2,000–2,800). In: C-Class, E-Class, S-Class, CLK, GLE, ML, G-Class.
- VW V10 TDI 5.0 — 42/100 → (in: VW Touareg) — complex, costly, and not worth the risk on the used market.
- VW/Audi 2.5 V6 TDI — 70/100 → — better than its reputation, but early engines (to about 2003–04) wear their camshafts and rockers, typically at 150,000–200,000 km; buy only with records of cam work. In: VW Passat; Audi A4, A6; Škoda Superb.
What to check before buying any used diesel
- Short-trip history kills diesels. A DPF needs motorway runs to regenerate. A car driven only around town will clog its DPF — a €400–1,200 job on a Hyundai/Kia 1.6 CRDi, more on others.
- Know where the timing chain lives. Rear-mounted chains (BMW N47) are the expensive ones. Belt-driven engines like the 1.9 TDI are cheap to service.
- Look for EGR and injector service records. EGR fouling is the most common moderate-cost diesel fault across almost every family here.
- Match the engine to your use. Buy a diesel only if you drive long distances regularly. For short urban trips, a reliable petrol or hybrid will cost you far less in the long run.
Check any engine's full issue list, repair costs, and mileage risk timeline on its EngineScope report before you buy.