Vehicles using OM604 engine list:

Engine OM604

Symptoms:
- Rough idling and poor acceleration
- Excessive smoke from the exhaust (black or white)
- Difficulty starting, especially when cold
- Loss of power and reduced fuel efficiency
- Engine warning light illumination

Diagnosis:
- Check for clogged fuel injectors or faulty injector seals causing poor fuel atomization
- Inspect the EGR valve for carbon buildup leading to rough running or stalling
- Test the glow plugs and glow plug relay for proper operation, especially in cold starts
- Examine the air intake system and turbocharger (if equipped) for leaks or blockages
- Perform compression test to rule out valve or piston ring wear
- Scan for fault codes related to sensors such as MAF, MAP, or coolant temperature sensor

Fixes:
- Clean or replace fuel injectors and injector seals to restore proper fuel delivery
- Remove and clean the EGR valve or replace if malfunctioning to prevent rough idling and emissions issues
- Replace faulty glow plugs and relay to improve cold start reliability
- Repair or replace damaged air intake components and check turbocharger condition
- Address any mechanical wear found during compression testing by repairing or rebuilding engine components
- Clear fault codes after repairs and verify engine performance improvements

Prevention:
- Use high-quality diesel fuel and regularly replace fuel filters to avoid injector clogging
- Perform routine maintenance on the EGR system to prevent carbon buildup
- Regularly check and replace glow plugs as part of cold weather preparation
- Maintain the air intake system and turbocharger with periodic inspections and cleaning
- Follow recommended oil change intervals with correct oil grade to ensure engine longevity
- Monitor engine performance and address warning signs early to prevent major failures