This bulletin provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components (e.g. intake valves and / or manifold, and combustion chambers).
full bulletin at NHTSA ↗2015 Subaru WRX engine problems
moderate 10 complaints filed with NHTSA · avg repair $3,100 · see engine across all vehicles →
Complaints
10
Recalls
0
Avg fix
$3,100
When does it fail?
Of the 10 engine complaints filed for the 2015 Subaru WRX, here's the actual mileage breakdown — failures cluster heaviest at 75,000-100,000 mi.
0-25k
25-50k
50-75k
75-100k
100-125k
125-150k
150k+
Each bar shows the share of total complaints filed at that mileage range. Peak failure window highlighted. Some owners report problems earlier; some make it well past 150,000 miles symptom-free. Maintenance habits and driving conditions shift the curve as much as mileage alone.
What stands out
Among the 6 model years of Subaru WRX in our records for engine problems, this one ranks #2 by owner-complaint volume.
Engine accounts for 19% of all owner complaints filed against this vehicle, across 5 categories tracked.
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering engine on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
This Bulletin provides the diagnostic procedure for the STARLINK® Remote Engine Start (RES).
full bulletin at NHTSA ↗This bulletin provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components (e.g. intake valves and / or manifold, and combustion chambers).
full bulletin at NHTSA ↗This bulletin announces the diagnostic procedures to be used when DTCs P2096 (POST CATALYST FUEL TRIM SYSTEM TOO LEAN BANK 1) and P2097 (POST CATALYST FUEL TRIM SYSTEM TOO RICH BANK 1) are detected by the Engine Control Module (ECM).
full bulletin at NHTSA ↗This Service Information Bulletin provides the Service Manual Correction to the diagnostic procedure for DTC B2A16 (Immobilizer Key Collation Diagnosis).
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
Ten owners report persistent engine troubles on 2015 WRX models. The most common complaint is rough idle and stalling, often triggered by cold starts or fueling, with RPM dropping between 400–1000 before the vehicle either recovers or stalls entirely. Multiple warning lights fire at once—check engine, cruise control, ABS, hill-start assist, traction control—suggesting electrical cascade faults rather than isolated component failure. One owner received a software update that temporarily resolved the issue; it returned at 9.7K miles. Two owners link their symptoms to Subaru recall 16V-162 (turbocharger air intake duct cracking) but report their vehicles weren't covered because they were manufactured before the recall's cutoff date.
More severe failures include a blown head gasket that vented white coolant vapor during highway driving without warning, rod knock (internal bearing noise) leading to short-block replacement at 55K miles, and bearing failure on a replacement short block at only 6,000 miles. One owner reports a secondary O2 sensor pump that failed at 55K miles and failed again identically at 90K, despite the 2014 model generation having a recall for the same part with the same part number. A direct-injection carbon buildup issue appears in one compression test, reducing airflow and cylinder pressure on a low-mileage engine.
Failure modes owners describe
Rough idle and stalling
Engine idles erratically between 400–1000 RPM, sometimes stalls, especially after fueling or on cold start. Multiple owners report vehicle entering limp mode with check engine light and other fault indicators lighting up simultaneously.
When: 9.7K miles; cold starts; variable timing
Symptoms owners cite: rough idle between 400–1000 RPM; vehicle stalling in neutral; sputtering on cold start; check engine light and multiple warning lights (cruise control, ABS, hill-start assist, traction control) tripping together; limp mode activation
Repairs/costs cited: Software update to engine computer performed; issue returned within weeks
Recalls/TSBs owners mention: Recall 16V-162 addresses turbocharger air intake duct cracking; owners report recall may not cover all affected VINs or production dates
Turbocharger intake duct cracking
Turbocharger air intake duct develops cracks due to incorrect material, reducing airflow and causing rough idle, reduced power, and stalling. Some vehicles manufactured before the recall date remain unaddressed.
When: Early production (pre-April 10, 2015 for some)
Symptoms owners cite: rough idle; reduced engine power; stalling; check engine light
Recalls/TSBs owners mention: NHTSA Recall 16V-162 issued but complainants report coverage gaps for certain production dates
Blown head gasket
Head gasket failure causing coolant to leak internally and externally. Engine coolant escapes as white vapor while driving, creating visibility hazard and environmental contamination.
When: No mileage reported; occurs during normal highway driving
Symptoms owners cite: white vapor cloud from engine while driving; coolant leak; no warning before failure
Repairs/costs cited: Confirmed by authorized Subaru dealer (Eastside Subaru, Kirkland, WA)
Rod knock and bearing failure
Engine develops rod knock (metallic clunking noise from internal engine damage). Two owners report bearing and short-block failures on low-mileage engines with proper maintenance. One owner's replacement short block spun a bearing at 6,000 miles.
When: 55K miles on original engine; 6K miles on replacement short block
Symptoms owners cite: clunking or knocking sound from engine; bearing noise
Repairs/costs cited: Short blocks replaced under warranty; replacement failed within 6,000 miles in one case
Secondary O2 sensor pump failure
Secondary O2 sensor pump burns out or remains continuously running, creating fire risk. Same design and part number used in 2014 models where recall was issued; 2015 remains unresolved.
When: 55K miles (first failure); recurred at 90K miles
Symptoms owners cite: check engine light; secondary O2 pump malfunction
Repairs/costs cited: Pump replaced under warranty at 55K; same fault returned at 90K
Recalls/TSBs owners mention: Recall issued for 2014 models with identical part; 2015 not covered
Direct injection carbon buildup
Carbon accumulation on intake valves (common in direct-injection engines) restricts airflow and causes low cylinder compression. Owners report this occurs without normal wear-and-tear progression.
When: Variable timing; identified during routine spark plug and compression testing
Symptoms owners cite: low compression on cylinder(s); rough running
Repairs/costs cited: Identified via compression test; carbon cleaning required
Synthesized from 10 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 3 most recent
The RPM drop and the engine stalls, but no check engine lights come on. It only happens in first gear, from what I've noticed.
Turbocharger intake cracked and causes the engine to have an extremely rough idle and stall. My vehicle has the same issue as NHTSA campaign number 16V16200 however it was manufactured before April 10th 2015 so it is not included in that recall.
Decided to get my spark plugs replaced, and got a compression test done while that service was done for convenience. Compression came out low on one side of my fa20dit engine. With more research, because the engine is direct injected, there is obvious build up on the intake valves, causing bad air flow. This is not a wear and tear issue.
Had engine trouble with your 2015 Subaru WRX?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the engine problem on the 2015 Subaru WRX?
It's a documented issue but not catastrophic. 10 complaints have been filed. Repairs average $3,100 and most owners catch it before it causes a breakdown.
At what mileage does the engine typically fail?
Based on the 10 complaints filed, engine issues most often appear around 70,675 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $3,100 for engine repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to engine?
No active recalls currently cover engine issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2015/Subaru/WRX.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.