2020-2022 Subaru Legacy & Outback 2.4L Turbo FA24F: Problems, Identification, and Used Replacement

Part Identification: Is This the Right Engine for Your Subaru?

The engine used in the 2020-2022 Subaru Legacy and Outback with the optional turbo is the FA24F, a 2.4-liter direct-injection turbocharged (DIT) flat-four "Boxer" engine. This specific assembly was only paired with a Continuously Variable Transmission (CVT). While Subaru uses the FA24F engine in other popular models like the Ascent and WRX, those versions are not direct replacements. They have different engine calibrations, wiring, oil pans, and mounting points that make them incompatible with the Legacy and Outback.

How to Confirm Fitment on Your Vehicle

Before purchasing a replacement engine, verify it is correct for your car using these steps:

1. Confirm Your Model: Ensure your vehicle is a 2020-2022 Subaru Legacy sedan or Outback wagon. This engine will not fit an Ascent, WRX, or any other model.
2. Check Your Engine: Your car must have the 2.4L turbocharged engine from the factory, not the standard 2.5L non-turbo engine. A quick visual check for the top-mounted intercooler and associated ducting can confirm this.
3. Verify Your VIN: The Vehicle Identification Number (VIN) is the most reliable way to confirm fitment. You can find it on a plate on the driver-side dashboard (visible through the windshield) and on a sticker in the driver-side door jamb.

Common Problems and Failure Symptoms

Severe engine trouble often shows clear symptoms. If you experience a combination of these, it may be time for a replacement assembly:

• Engine knocking or loud metallic sounds, which could indicate rod bearing failure.
🎬 Listen: How to identify Subaru rod knock vs piston slap
• Excessive blue or white smoke from the exhaust, signaling internal oil or coolant leaks.
• Catastrophic failure resulting in a hole in the engine block.
• A persistent check engine light with timing-related codes that are not resolved by other repairs.
• Metal shavings found in the engine oil and filter during an oil change.
• Rattle-type or fluttering sounds during acceleration caused by cracking in the front exhaust pipe.

Diagnostic Flowchart

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

This engine generation is subject to several recalls and service bulletins. Always check with a Subaru dealer using your VIN to see which apply to your specific vehicle.

Severe Issues & Recalls

Moderate & Minor Issues

What's Included in a Used Engine Assembly?

A used engine is typically sold as a "long block." This includes the core internal components but not the accessories that bolt onto the outside. You or your mechanic will need to transfer these parts from your old engine.

Replacement Cost Estimates

Costs can vary based on part availability, location, and shop labor rates. These are estimates for the North American market.

Installation: Critical Steps and Common Mistakes

Replacing this engine is an expert-level job that requires special tools and procedures. Professional installation is highly recommended.

Special Tools Required

• Engine hoist with a load leveler
• Subaru-specific engine stand adapter
• Torque wrench
• Fuel line quick-disconnect tools
• High-pressure fuel system tools
• Bi-directional scan tool (Subaru Select Monitor IV or equivalent)
• Cam sprocket wrenches

Required Programming & Calibration

Essential Replacement Parts & Fluids

Always use new consumables during an engine swap to ensure reliability. Do not reuse old gaskets or fluids.

Installation Gotchas

• Fragile Oil Level Switch & Solenoids: The oil level switch and variable valve timing (AVCS) solenoids are highly fragile and easily cracked during an engine swap.
• High-Pressure Fuel Line Replacement: The high-pressure fuel lines running from the high-pressure fuel pump (HPFP) to the injectors are single-use only and must be replaced.
• Precise RTV Application: Excess RTV sealant on the timing cover or oil pan can break off internally, clog the oil pickup screen, and cause catastrophic bearing failure.
• CVT Cooler Lines: Engines from automatic vehicles may have extra coolant lines for a CVT cooler that need to be properly looped or capped if your setup differs.
• Ground Straps: Ensure all engine-to-chassis ground straps are clean and securely reconnected to prevent electrical issues.
• Harness Compatibility: You must transfer your original engine wiring harness to this replacement engine to ensure all sensor connectors, routing, and pinouts match your vehicle perfectly.

What Fails at Every Mileage Band

Under 60,000 Miles

Engines in this range are generally healthy, but early production units may have factory defects. Factory recalls for the Transmission Control Unit (TCU) and inhibitor switch are the most significant issues. Some early 2.4L turbo engines experienced oil pan leaks due to faulty RTV sealant application from the factory. Software glitches in the large infotainment screen are common, and TSBs exist for timing-related DTCs and minor oil leaks from the oil level sensor O-ring.

• ✓Do during install (required): Replace engine oil, coolant, and differential fluids.
• ✓Do during install (recommended): Proactively replace the O-ring for the oil level switch/sensor to prevent future leaks (per TSB 02-190-22R).
• ✓Cheap insurance while the engine is out: Replace the spark plugs (the factory interval is 60,000 miles, making this the perfect time). Inspect and consider replacing the PCV valve, which is critical for crankcase pressure regulation. Inspect the serpentine drive belt for cracks or wear and replace if necessary.

60,000 - 100,000 Miles

In this band, carbon buildup on the intake valves becomes a more prominent issue, which is a known characteristic of direct-injection-only engines like the FA24F. Some owners report CVT transmission issues or failures in this range. Oil consumption can become more noticeable, and wear on suspension components may become apparent.

• ✓Do during install (required): Thoroughly inspect the turbocharger for any signs of oil leaks, shaft play, or damage, especially if the previous engine failed. Perform all 'Under 60K' required items.
• ✓Do during install (recommended): This is the ideal mileage to perform a manual intake valve cleaning (walnut blasting) service to remove carbon deposits from the intake valves and ports, restoring performance and efficiency.
• ✓Cheap insurance while the engine is out: While Subaru has varying recommendations, inspecting or replacing the CVT fluid is wise, as the fluid condition is critical to the transmission's longevity.

100,000 - 150,000 Miles

If not previously addressed, carbon buildup can lead to noticeable performance degradation, rough idling, and misfires. The likelihood of issues with high-stress components like the turbocharger increases. Age-related leaks from seals and gaskets become more common. Rod bearing failure, while not as common as on older Subaru engines, can occur, often preceded by a knocking noise and linked to oil contamination or low oil levels.

• ✓Do during install (required): Replace all rubber coolant and vacuum hoses, as they become brittle with age and heat cycles.
• ✓Do during install (recommended): Install a full gasket and seal kit. While the engine is out, it is cost-effective to replace all major gaskets and seals, including front and rear main seals, valve cover gaskets, and oil pan sealant.
• ✓Cheap insurance while the engine is out: Replace the water pump and thermostat, which are critical cooling components that are much easier to replace with the engine removed. Although designed to last the engine's life, inspect the timing chain, guides, and tensioners for wear (the plastic guides are a point of long-term evaluation).

Real Owner Experiences

Repair or Replace?

Deciding whether to repair your current engine or replace it with a used assembly depends on the severity of the failure and the cost of labor.

When Repair Makes Sense

• Oil Leaks (Oil Level Switch O-ring, Oil Pan Sealant): This is almost always a repair. A simple O-ring is cheap, but a full engine reseal to fix a major leak can cost thousands because the engine must be removed (one dealership quoted $4,013 for a full reseal). Typical repair costs range from $500 to $4,000+.
• Carbon Buildup on Intake Valves: This is a routine maintenance item for direct-injection engines, not a cause for replacement. It typically costs $350 to $700 and is performed every 50,000-60,000 miles to restore performance.
• Failed Head Gasket: If the engine has not overheated severely and there is no other internal damage, repairing the head gaskets can be cost-effective. Quotes vary widely from $2,700 to $8,000. If the repair cost approaches the price of a low-mileage used engine, replacement becomes a more attractive option.

When Replacement is the Smarter Choice

Replacement is the smarter choice in cases of catastrophic internal failure, such as a spun rod bearing, broken connecting rod, severe oil starvation, or significant damage from a timing or CVT chain failure. If repair costs exceed 50-75% of the vehicle's market value or the cost of a quality used engine (which typically run $1,850 to $5,500), replacement offers better value and often comes with a warranty.

Freight & Delivery Reality

Used engine assemblies are large, heavy industrial parts. They do not ship like standard parcels.

• Size and Weight: A complete FA24F engine assembly weighs approximately 475 lbs and measures roughly 40" x 42" x 36" before crating.
• Shipping Method: It will ship as Less-Than-Truckload (LTL) freight on a wooden pallet.
• Delivery Requirements: You must have a commercial address with a forklift or loading dock, or request a truck with a liftgate for residential delivery.
• Inspection: Always inspect the engine for physical damage (like cracked sensors or broken timing covers) before signing the driver's delivery receipt.
• Pre-Purchase Verification: A reputable seller will conduct a pre-purchase verification interview to confirm your VIN, body style, and engine type to ensure you are getting the exact match for your Legacy or Outback.

Before the First Start: Priming and Fluids

A used engine drains its fluids while sitting in storage. Starting it dry will cause instant damage to the internal parts and the turbocharger. You must add fresh fluids and prime the oil system (pump oil through the engine before it actually runs) before starting the car.

Mandatory Fluids

• Engine Oil: Use fresh 0W-20 full synthetic motor oil. Look for the API SP or ILSAC GF-6A certification on the bottle. Always install a brand new oil filter.
• Engine Coolant: Use Subaru Super Coolant (Blue) or an equivalent 50/50 pre-mixed phosphate-enhanced OAT (Organic Acid Technology) coolant. Do not mix older green coolants with the modern blue fluid.

Oil Priming Procedure

Follow these steps to build oil pressure safely before the engine fires up:

1. Fill the engine with the correct amount of fresh oil and coolant.
2. Disable the fuel system so the engine cannot start. The easiest way to do this is to remove the fuel pump fuse from the fuse box.
3. Crank the engine (turn the key or hold the start button) for 10 to 15 seconds.
4. Stop and wait 30 seconds. This gives the starter motor time to cool down so it does not burn out.
5. Repeat this cranking process until the red low oil pressure warning light turns off on the dashboard.
6. Reinstall the fuel pump fuse.
7. Start the engine normally. Let it idle and check underneath the vehicle for any fluid leaks.

Frequently Asked Questions (FAQ)