2021 Freightliner FL Parts
The 2021 Freightliner FL came with 3 engines (3.0L L4 DIESEL Turbocharged, 3.9L L4 DIESEL Turbocharged, 6.4L L6 DIESEL Turbocharged), and the right parts depend on which one you have. We list 47 parts across all of them — each category page below covers every engine, and each row shows which engine(s) it fits.
Every part carries its brand and manufacturer part number, so you can compare OEM-grade and aftermarket options for the same fitment and cross-reference the number against the part you're replacing before anything goes in the cart.
Browse by Engine
3.0L L4 DIESEL Turbocharged
10 parts · 2 categories Verified fitment3.9L L4 DIESEL Turbocharged
15 parts · 3 categories Verified fitment6.4L L6 DIESEL Turbocharged
22 parts · 6 categories Verified fitmentNot sure which engine you have? Check the emissions label under the hood, your registration, or decode the VIN — the 8th character usually identifies the engine.
Parts by Category
Cooling System Parts
27 parts · 1 subcategory · 2 brands Verified fitment Keeps operating temperature in the narrow band the engine was designed for, from radiator and water pump to thermostat and hoses.Electrical Parts
3 parts · 1 subcategory · 1 brand Verified fitment Covers charging, starting and the sensors and modules the vehicle relies on, from alternator and starter to oxygen sensors.Engine Parts
1 part · 1 subcategory · 1 brand Verified fitment Covers the internals and hard parts that build compression and keep oil where it belongs — gaskets, bearings, camshafts, lifters, seals and timing components.Exhaust & Emission Parts
10 parts · 1 subcategory · 1 brand Verified fitment Carries combustion gases out safely and keeps emissions equipment — catalytic converters, O2 sensors, EGR — doing its job.Fuel & Air Parts
5 parts · 2 subcategories · 2 brands Verified fitment Meters fuel and air — pumps, injectors, filters, intake components and the sensors that balance the mixture.Heat & Air Conditioning Parts
1 part · 1 subcategory · 1 brand Verified fitment Keeps the cabin comfortable and the windshield clear through the compressor, condenser, evaporator, heater core and blower.Each category page covers all 3 engine options for the 2021 Freightliner FL — every part shows the engine(s) it fits, and an on-page filter narrows it to yours.
Confirm your configuration
Other Freightliner FL Years
Getting Fitment Right on the 2021 Freightliner FL
Most wrong-part orders for the 2021 Freightliner FL trace back to the engine choice: with 3 options listed, components that look interchangeable — cooling parts, tensioners, mounts, sensors — often carry different part numbers per engine. Each row shows which engine(s) it fits, and each category page filters to one engine at a time.
Every part across the 6 categories shows its brand and manufacturer part number. Use the number to cross-reference: match it to the part coming off the vehicle, compare an OEM-supplier part against its aftermarket equivalent, or verify a shop's estimate line by line. When a number is discontinued, the same-fitment parts around it are the fastest path to a current replacement.
Frequently Asked Questions
How many parts fit the 2021 Freightliner FL?
We list 47 parts for the 2021 Freightliner FL, organized into 6 categories across 3 engine options. Every part includes the brand, manufacturer part number and fitment notes.
Which engines came in the 2021 Freightliner FL?
Our records list 3.0L L4 DIESEL Turbocharged, 3.9L L4 DIESEL Turbocharged, 6.4L L6 DIESEL Turbocharged. Parts frequently differ between them — a part verified for one engine is not guaranteed to fit another — so identify your engine first (emissions label under the hood, or the VIN's 8th character), then use the engine filter on each category page.
Are OEM and aftermarket parts both available for the 2021 Freightliner FL?
Yes — parts come from original-equipment suppliers and established aftermarket brands, shown side by side with their part numbers where both cover the same fitment. Cross-referencing those numbers is how you confirm an aftermarket part genuinely replaces the OEM one.
How do I verify a part number fits my 2021 Freightliner FL?
Search the number on this site: the result shows the part, its brand and every configuration with published fitment. If your exact year, model and engine appear in that list, the number is a match. The notes column carries any remaining qualifiers — position, trim or production date.
Manufacturer names, model designations and part numbers are used for identification and fitment reference only. AutoFactsDB is an independent catalog and is not affiliated with, endorsed by, or sponsored by any vehicle manufacturer displayed on this page.