Subaru WRX 2015–2021Common problems, reliability & repair costs

Symptoms: Bottom-end knock or metallic rattle (often loudest cold), low oil pressure, sudden catastrophic failure sometimes with no prior warning. Spun bearings have been reported on near-new short blocks.

Fix: There is no cheap fix once a bearing spins. The realistic repair is a rebuilt/forged short block or a complete engine replacement (often an upgraded IAG/built short block on enthusiast cars). Critically, Subaru's crankshaft-bearing warranty extension applied to the EJ turbo short block, NOT the FA20DIT — so most WRX owners pay out of pocket. Strict oil-change discipline and avoiding sustained high-load/lean conditions is the main prevention.

Sources: CarComplaints — 2015 WRX engine problems, NASIOC — rod bearing failure stories (community thread), ClubWRX — spun bearing owner reports

Symptoms: Cylinder-4 misfire, blue smoke, knock, low compression on one cylinder, sudden power loss. Ringland failure typically follows detonation; rod-bearing failure follows oil starvation or hard use.

Fix: Built or reman short block / full engine replacement. Subaru did extend the New Car Limited Powertrain Warranty on the turbocharged 2.5L EJ short block from 5yr/60k to 8yr/100k miles for the isolated crankshaft-bearing condition (TSB/warranty extension, covering 2012–2014 WRX and 2012–2017 STI) — verify by VIN. Beyond that window or for ringland failure, it's a paid rebuild.

Sources: NHTSA — Subaru crankshaft bearing service bulletin 02-181-19 (PDF), OEMDTC — Crankshaft Bearing Warranty Extension (2012–2014 WRX, 2012–2017 STI)

Symptoms: Slow, invisible power loss; rough cold idle in later stages; reduced airflow with no check-engine light. Direct injection sprays fuel past the valves, so nothing washes oil-vapor carbon off the intake-valve backs the way port injection does.

Fix: Walnut-blast the intake valves (media blasting the carbon off with the intake manifold removed). Recommended roughly every 60k–100k miles. Many owners add a quality air-oil separator (AOS) to cut the oil vapor feeding the buildup. This is maintenance, not a defect — budget for it like brakes.

Sources: ThreePiece — FA20DIT carbon buildup explained, ClubWRX — carbon buildup on valves (owner thread)

Symptoms: Clutch judder/shudder when releasing from a stop, slipping, a throwout-bearing whine that changes with pedal position, or outright clutch failure. CarComplaints lists clutch issues as the single most-complained-about area on the 2015 WRX.

Fix: Replace the clutch disc, pressure plate, throwout bearing, and usually the flywheel — transmission-out labor, which is most of the cost. Subaru issued a TSB and a release-bearing design change; some early cars were repaired under warranty. Out of warranty, many owners step up to a stronger aftermarket clutch.

Sources: CarComplaints — 2015 WRX clutch problems, ClubWRX — TSB for clutch shudder (owner thread)

Symptoms: Shudder, hesitation, or delayed engagement at low speed and light throttle, especially when cold — classic torque-converter / valve-body symptom.

Fix: Mild cases are sometimes addressed with a fluid service or valve-body/solenoid work; a failed unit can mean a $4,000–$7,000 replacement. Subaru issued extended warranties and TSBs on Lineartronic units for shudder/valve-body issues — check coverage by VIN. The manual avoids this entirely.

Sources: Rick's Free Auto Repair Advice — Subaru CVT reliability & common issues, Subaru Outback Forums — TR690 problems (owner thread)

Symptoms: Growl or hum from a corner that rises with speed and changes when you load the car in a turn. A normal high-mileage AWD wear item, reported across the chassis.

Fix: Replace the affected wheel-bearing/hub assembly. Straightforward per-corner job; not a design defect, just wear — but worth catching at inspection because owners often hear it and ignore it.

Sources: TorqueBot — Subaru WRX common problems

Tools: Flat screwdriver, Shop rag

1. Unclip the airbox lid (no tools needed on most VA cars) and lift it to expose the panel filter.
2. Lift out the old engine air filter, noting orientation; wipe out any debris in the box.
3. Drop in the new panel filter and re-clip the lid.
4. For the cabin filter, open the glovebox, release the side stops to drop it fully, and pull the filter housing cover.
5. Slide out the old cabin filter and insert the new one with the airflow arrow pointing the same direction as the old one.

Tools: Floor jack + jack stands (or ramps), Oil filter wrench (cartridge/cap-style for FA, spin-on for EJ), Drain pan, funnel, torque wrench

1. Warm the engine briefly, then lift the front and support it safely on stands.
2. Remove the splash guard, position the drain pan, and remove the drain plug to drain the oil; replace the crush washer.
3. Remove and replace the oil filter (the FA20DIT uses a top-mounted filter; the EJ257 a conventional spin-on); pre-fill if accessible.
4. Reinstall the drain plug to spec, then refill with the correct Subaru-spec synthetic oil and weight.
5. Run the engine, check for leaks, shut off, wait, and verify level on the dipstick. On the FA, recheck the level over the next few weeks — these engines can consume oil.

Tools: Socket set, Hose cutters, Pliers / hose-clamp tool, Shop towels

1. Locate the PCV/crankcase-vent plumbing routing oil vapor toward the intake.
2. Mount the AOS catch-can/separator per the kit's bracket location, away from extreme heat.
3. Reroute the crankcase-vent hoses through the AOS inlet and outlet per the kit instructions, trimming hoses to length.
4. Secure all hoses with clamps and confirm no kinks or vacuum leaks.
5. Start the engine, check for leaks and correct idle, and plan to empty the AOS at oil-change intervals.