OM668
Mercedes-Benz · OM668 1.7 Diesel
1998–2004
"W168 A-Class. Same era as M166 petrol. Injector issues. Head gasket concerns. Turbo failure on higher-output version. Not Mercedes' best diesel. Better alternatives exist."
Mileage Risk Timeline
When problems typically appear — enter your mileage to see your risk zone
Known Issues 2
Head gasket failure
▸Coolant loss, smoke
W168 diesel head gasket known weak.
Φλάντζα W168 diesel — €500-1,200.
Injector failure
▸Rough idle, smoke
Early CDI injectors.
Μπεκ — €300-800.
Models with OM668 2
Related Guides
Other Mercedes-Benz Engines
Tuning Potential
Minimal
Frequently Asked Questions
Is the Mercedes-Benz OM668 reliable?
The Mercedes-Benz OM668 scores 58/100 with a verdict of CAUTION. It has 2 documented issues with total repair costs between €800 and €2,000.
What are the common problems with the OM668?
The most common issues are:
- Head gasket failure — high, repair cost €500–€1,200, 80,000 km–150,000 km
- Injector failure — moderate, repair cost €300–€800, 80,000 km–150,000 km
What cars use the Mercedes-Benz OM668?
How much does it cost to repair the OM668?
Total potential repair costs for all 2 known issues range from €800 to €2,000. The most expensive issue is typically .
What years was the OM668 produced?
The Mercedes-Benz OM668 was produced from 1998 to 2004. It is a 1689cc I4 diesel engine.
Scores are calculated from documented issues, repair costs, and failure patterns across thousands of owner reports and technical sources. Learn about our methodology. Always inspect before you buy.