C200 / C220 CDI 2.1 (OM646, to 2009)

2007–2009 · diesel · 2148cc · 170hp

Engine codes: OM646

Reliable

Reliability, common problems and owner reviews for the Mercedes Benz C-Class W204 C200 / C220 CDI 2.1 (OM646, to 2009). Check this before you buy used.

The older 2.1 CDI — noisy but close to invincible. Simpler than the OM651 that replaced it, with fewer emissions complications. The choice for high-mileage drivers who want a durable W204 diesel.

Same engine, other cars

This is the same physical engine (OM651) sold under different names across brands. Reliability is broadly shared — cross-check these:

Known Issues

Injector / EGR wear (high mileage)recurring

Injectors and EGR wear at high mileage but are robust overall.

Fix / Workaround: Service injectors/EGR as needed.

Repair cost: €200–€900

Typically appears after: 250,000 km

Noisy operationminor

Characteristically clattery — not a fault.

Fix / Workaround: None needed.

Year Cutoffs

2009: Before — OM646 — simpler, very durable. After — Replaced by OM651 (more complex).

Mileage Thresholds

After 300,000 km: Commonly reached; high-mileage favourite.

Pre-Purchase Checklist

☐Confirm it's the OM646 (pre-2009)
☐The durable high-mileage diesel choice
☐Accept the noise

Frequently asked questions

Is the Mercedes Benz C-Class W204 C200 / C220 CDI 2.1 (OM646, to 2009) reliable?

Reliable — The older 2.1 CDI — noisy but close to invincible. Simpler than the OM651 that replaced it, with fewer emissions complications. The choice for high-mileage drivers who want a durable W204 diesel.

What are the common problems and reviews for the Mercedes Benz C-Class W204 C200 / C220 CDI 2.1 (OM646, to 2009)?

The most commonly reported problems: Injector / EGR wear (high mileage), Noisy operation.

Is a used Mercedes Benz C-Class W204 C200 / C220 CDI 2.1 (OM646, to 2009) worth buying?

Minor issues only, easy to maintain, no design flaws. A safe used buy.