5 Fuel & air parts are listed for the 2021 Freightliner FL, in 2 part types, covering all 3 engine options (3.0L L4 DIESEL Turbocharged, 3.9L L4 DIESEL Turbocharged and 6.4L L6 DIESEL Turbocharged). Each one has a brand, a manufacturer part number and notes that say where it fits.
The fuel & air system on the 2021 Freightliner FL meters fuel and air — pumps, injectors, filters, intake components and the sensors that balance the mixture. All 5 listed parts are Fuel Filter (4 parts) and Air Filter (1 part).
The 2021 Freightliner FL was sold with 3 engines. Every part on this page is engine-specific. Each part shows which engine(s) it fits.
The most listed brands for 2021 Freightliner FL fuel & air parts are WIX (4 parts) and HENGST (1 part).
Each part number listed for the 2021 Freightliner FL opens a page with every vehicle that part fits.
Air Filter
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| WIX Fits: 6.4L L6 DIESEL Turbocharged | 46744 | 🇲🇽 MX | Radial Seal Outer Air | View on Amazon |
This table covers the engine air filters in the intake box. Typical signs include hesitation, a dirty film in the air box, or a filter so packed it collapses. Seat the new filter in the box so unfiltered air cannot bypass the seal.
This group shows a single part: WIX 46744.
Fuel Filter
| Brand | Part Number | Markets | Notes | Buy |
|---|---|---|---|---|
| HENGST Fits: 6.4L L6 DIESEL Turbocharged | E52KPD36 | 🇲🇽 MX | View on Amazon | |
| WIX Fits: 6.4L L6 DIESEL Turbocharged | 33634 | 🇲🇽 MX | Cartridge FilterCartridge Fuel Metal Free Filter | View on Amazon |
| WIX Fits: 6.4L L6 DIESEL Turbocharged | 33412 | 🇲🇽 MX | Spin-On Fuel/Water Separator Filter | View on Amazon |
| WIX Fits: 6.4L L6 DIESEL Turbocharged | 33812 | 🇲🇽 MX | Spin-On Fuel/Water Separator Filter | View on Amazon |
This table covers the fuel filters in the line or at the tank. Typical signs include restricted flow — long cranking, weak airflow, or dirty fluid after a short interval. Seat the new filter so it cannot bypass, and use the grade the notes call for.
4 Fuel Filter parts for the 2021 Freightliner FL come from 2 brands — WIX and HENGST.
This group includes HENGST E52KPD36, WIX 33634 and WIX 33412 and the remaining parts above.
Buying Fuel & Air Parts for a 2021 Freightliner FL
On this vehicle, the fuel & air system meters fuel and air — pumps, injectors, filters, intake components and the sensors that balance the mixture.
- Match the engine first. Every fuel & air part here is engine-specific; each row shows which engine(s) it fits.
- Read the notes on each row for position, trim and spec qualifiers before you order.
- Where labor overlaps, check the air filter with any intake or injector work — a clogged filter skews every mixture reading downstream.
- Cross-reference the manufacturer part number against your old part or a service-manual listing.
Start with the largest groups on this page: Fuel Filter and Air Filter .
Frequently Asked Questions
How many fuel & air parts fit the 2021 Freightliner FL?
Our catalog currently lists 5 fuel & air parts for the 2021 Freightliner FL across 2 subcategories and 2 brands, covering all 3 engine options (3.0L L4 DIESEL Turbocharged, 3.9L L4 DIESEL Turbocharged and 6.4L L6 DIESEL Turbocharged). Each part is matched to the engine(s) it fits.
Do fuel & air parts differ between 2021 Freightliner FL engines?
Yes. Every fuel & air part on this page is engine-specific. Each row shows which engine(s) it fits — use the filter at the top to hide the rest. If you're unsure which engine you have, check the emissions label under the hood or the 8th character of your VIN.
What are the signs of fuel & air problems on a 2021 Freightliner FL?
Common symptoms include long cranking before start, hesitation under acceleration, worsening fuel economy, or a whining fuel pump. If you notice any of these, identify the affected subcategory above and cross-reference the part numbers listed.
What should I replace at the same time?
Where labor overlaps, check the air filter with any intake or injector work — a clogged filter skews every mixture reading downstream.
What do the market flags (US, CA, MX) on each part mean?
They show the market for which the manufacturer published application data for that part — where the vehicle was first sold, not where the part was made. If your 2021 Freightliner FL was originally sold in the US, the safest choice is a part marked for the US market.
How do I make sure a part fits my 2021 Freightliner FL?
First match the engine — each row shows which engine(s) the part fits. Then replace the fuel filter when doing a pump, and never run a new pump on a near-empty rusty tank — debris is what killed the old one. The notes column carries position and trim qualifiers where they apply.
Other Parts for the 2021 Freightliner FL
Fuel & Air Parts for Other Freightliner FL Years
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