Vehicles using OM668.940 engine list:

Engine OM668.940

Symptoms:
- Rough idling and loss of power
- Excessive smoke from the exhaust (black or white)
- Hard starting or failure to start
- Engine warning light illumination
- Unusual noises from the injection pump area

Diagnosis:
- Check for clogged or dirty fuel injectors causing poor atomization
- Inspect the fuel filter for blockages restricting fuel flow
- Test the glow plugs for proper operation, especially in cold conditions
- Examine the injection pump for leaks or mechanical wear
- Scan for fault codes related to the engine management system
- Inspect the EGR valve for carbon buildup causing rough running

Fixes:
- Replace or professionally clean fuel injectors to restore proper spray pattern
- Change fuel filters regularly to maintain clean fuel supply
- Replace faulty glow plugs to improve cold start performance
- Repair or replace the injection pump if leaks or internal damage are found
- Clean or replace the EGR valve to prevent rough idling and emissions issues
- Use quality diesel fuel and additives to keep the fuel system clean

Prevention:
- Adhere to scheduled maintenance intervals, including fuel filter changes every 20,000 km
- Use high-quality diesel fuel to reduce injector and pump wear
- Avoid prolonged idling to minimize carbon buildup in the EGR and intake system
- Regularly check and replace glow plugs as needed, especially before winter
- Perform periodic diagnostic scans to catch issues early before they cause damage

The OM668.940 engine is generally reliable but sensitive to fuel quality and maintenance. Keeping the fuel system clean and components in good condition will ensure smooth operation and longevity.