Vehicles using OM642.856 engine list:

Engine OM642.856

Symptoms:
- Rough idling and loss of power
- Excessive smoke from the exhaust (black or blue)
- Engine warning light illumination
- Increased oil consumption or oil leaks
- Difficulty starting or misfires

Diagnosis:
- Check for turbocharger faults, as the turbo can fail or have actuator issues
- Inspect the EGR (Exhaust Gas Recirculation) valve for clogging or malfunction
- Perform a compression test to detect cylinder wear or injector problems
- Scan for fault codes related to fuel system, sensors, or emission controls
- Examine the timing chain and tensioner for wear or noise, as premature wear is common

Fixes:
- Clean or replace the EGR valve to restore proper exhaust flow and reduce smoke
- Repair or replace the turbocharger or its actuator if faulty
- Replace worn injectors or seals to fix misfires and oil leaks
- Renew timing chain components if wear or slack is detected to prevent engine damage
- Use OEM parts and ensure proper oil quality and change intervals to maintain engine health

Prevention:
- Regularly service the engine with high-quality oil and adhere to recommended oil change intervals
- Avoid short trips that prevent the engine from reaching optimal operating temperature, reducing carbon buildup
- Use fuel additives or periodic cleaning to minimize injector and EGR clogging
- Monitor engine performance and address warning lights promptly to prevent escalation
- Maintain the cooling system to avoid overheating, which can accelerate wear on engine components

By following these diagnostic steps and maintenance practices, owners of Mercedes Benz E 350 CDI and E 350 d models equipped with the OM642.856 engine can mitigate common issues and extend engine longevity.