Piezo injectors (2009–2011)
usually 60,000–140,000 km · High risk
Signs: Rough running, knocking, no-start
Fix: Replace injectors (check campaign)
€1,000–2,500
Engine: common problems, timing drive and oil
2.1 CDI (Mercedes OM651)
Diesel · 1,796 / 2,143 cm³ · 70–150 kW
19
model generations
3
known faults
2,100,000
new cars in the EU (2010–2025)
Enter your VIN and mileage and get a plan built for your exact engine and gearbox.
Fuel: Diesel. Timing drive: chain.
In our database this engine is fitted to 19 model generations, among them: Mercedes-Benz C-Class (W205), Mercedes-Benz E-Class (W212), Mercedes-Benz GLC (X253), Mercedes-Benz GLA (X156), Mercedes-Benz Vito (W447), Mercedes-Benz A-Class (W176) and 13 more.
The most expensive known risk is piezo injectors (2009–2011): it usually appears at 60,000–140,000 km and costs €1,000–2,500 to fix.
Key facts
| Fuel | Diesel |
|---|---|
| Displacement | 1,796 / 2,143 cm³ |
| Power | 70–150 kW |
| Years | 2008–2019 |
| Timing drive | Chain |
| Oil | 5W-30 · MB 229.51 / 229.52 · ~6.5 L · every 15,000 km |
| Engine codes | OM651 |
Known engine faults
Faults that belong to the engine itself. They apply to every model with this engine, and each model has its own extra faults on its model page.
Timing chain stretch
usually 200,000–280,000 km · Medium risk
Signs: Correlation codes, rattle
Fix: Replace chain
€1,200–2,200
EGR / DPF
usually 150,000–220,000 km · Medium risk
Signs: Limp mode, DPF light
Fix: Clean or replace
€300–1,500
Engine-related service
Intervals and typical prices, using the Mercedes-Benz C-Class (W205) as an example. The app gives the exact plan for your car.
| Item | Interval | Typical price |
|---|---|---|
| DPF health check (soot / ash load)Emissions | every 20,000 km | €0–60 |
| Engine oil + oil filterEngine | every 15,000 km or every 12 months | €70–150 |
| Air filterEngine | every 30,000 km or every 24 months | €15–45 |
| Fuel filterFuel | every 30,000 km or every 24 months | €40–110 |
| Glow plugsEngine | every 100,000 km | €120–300 |
| Auxiliary (serpentine) beltEngine | every 120,000 km | €70–180 |
| Coolant replacementCooling | every 150,000 km or every 96 months | €70–150 |
| Timing chain inspection (listen on cold start)Engine | every 150,000 km | €0–120 |
Models with this engine
Model generations this engine is fitted to.
Infiniti Q30 / QX30 2015–2019Infiniti Q50 2013–2023Mercedes-Benz A-Class (W176) 2012–2018Mercedes-Benz B-Class (W246) 2011–2018Mercedes-Benz C-Class (W204) 2007–2014Mercedes-Benz C-Class (W205) 2014–2021Mercedes-Benz CLA (C117) 2013–2019Mercedes-Benz CLS (C218) 2011–2018Mercedes-Benz E-Class (W212) 2009–2016Mercedes-Benz E-Class (W213) 2016–2023Mercedes-Benz GLA (X156) 2013–2020Mercedes-Benz GLC (X253) 2015–2022Mercedes-Benz GLK (X204) 2008–2015Mercedes-Benz ML / GLE (W166) 2011–2019Mercedes-Benz SLK / SLC (R172) 2011–2020Mercedes-Benz Sprinter (906) 2006–2018Mercedes-Benz Sprinter (907 / 910) 2018–Mercedes-Benz Vito (W447) 2014–Mercedes-Benz Vito (W639) 2003–2014
Common questions
Does the 2.1 CDI (Mercedes OM651) engine have a timing chain or a timing belt?
Chain.
What oil does the 2.1 CDI (Mercedes OM651) engine take?
5W-30 · MB 229.51 / 229.52 · ~6.5 L · every 15,000 km.
What are the known problems with the 2.1 CDI (Mercedes OM651) engine?
The faults with the highest risk: piezo injectors (2009–2011) (60,000–140,000 km, €1,000–2,500); timing chain stretch (200,000–280,000 km, €1,200–2,200); EGR / DPF (150,000–220,000 km, €300–1,500).
Which cars have the 2.1 CDI (Mercedes OM651) engine?
Mercedes-Benz C-Class (W205), Mercedes-Benz E-Class (W212), Mercedes-Benz GLC (X253), Mercedes-Benz GLA (X156), Mercedes-Benz Vito (W447), Mercedes-Benz A-Class (W176) and 13 more.
Sources and notes
Faults, intervals and prices are indicative and collected from public sources and owner experience; always rely on the service book and a qualified workshop. Test statistics: DVSA – Anonymised MOT tests and results, Open Government Licence v3.0. Dutch tests: RDW Open Data (CC0). Engine versions: EEA, monitoring of CO₂ emissions from new passenger cars (CC BY 4.0, DG CLIMA). Owner complaints: NHTSA ODI (public domain). Recalls: DVSA Vehicle Safety Branch Recalls Database, OGL v3.0. Brand and model names are trademarks of their owners and are used only to describe the vehicles.
Updated 08/10/2026