Fuel
Fuel Filter
The fuel filter removes dirt and water before fuel reaches the pump or injectors.
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Fuel delivery flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Traps particles that would wear the pump and injectors
- Separates water in diesel systems
- Protects the high-pressure rail
When it fails
- Loss of power under load
- Hard starting
- Fuel starvation on hills
- Diesel: water-in-fuel warning
How to diagnose
- Check fuel pressure before and after the filter
- Inspect the filter for contamination
- Drain water from diesel filters
Maintenance
- Replace every 20,000–40,000 km or per the manual
- Use the correct filter spec
- Bleed the system after changing a diesel filter
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.