Knock control limited by ECU on lower-octane fuel; rod bends, then catastrophic failure.
Reviewed by SubaruReview Editorial Team · Last reviewed 2026-05-15 · Editorial standards
How this problem ranks against the other documented WRX / STI failures — cost, severity, and DIY difficulty at a glance.
| Problem | Years | Severity | Repair cost | DIY |
|---|---|---|---|---|
| WRX FA20 Bent Connecting Rod (this page) | 2015-2021 | Critical | $6,500–$11,000 | 5/5 |
| EJ255/EJ257 Ringland Failure | 2008-2014 | Critical | $4,500–$8,500 | 5/5 |
| EJ257 Rod Bearing Failure & STI Rod Knock (2004-2021) | 2004-2021 | Critical | $400–$12,000 | 5/5 |
| 2022+ WRX FA24 RTV Oil Pickup Clog | 2022-2024 | Critical | $2,200–$4,000 | 4/5 |
| Subaru WRX Turbo Banjo Bolt Screen Oil Starvation | 2002-2014 | Critical | $400–$2,500 | 4/5 |
This is one of several documented WRX / STI problems we track, and it fits inside the broader WRX & STI guide. If you're weighing repair against replacement, cross-check the Subaru repair-cost database and any open NHTSA recalls on your VIN before booking a shop.
Knock control limited by ECU on lower-octane fuel; rod bends, then catastrophic failure.
Aggressive timing tables + 91-octane minimum not always met.
Aggressive timing tables + 91-octane minimum not always met.
National average $6,500–$11,000.
Difficulty 5/5. Long-block replacement; consider stage-1 protective tune.
Knock under load; Loss of power; Eventual rod knock
Owners typically pay $6,500–$11,000 at an independent Subaru shop, parts and labor included. Our Subaru Head Gasket Replacement Cost guide breaks the job down by parts, labor hours, and where the money actually goes.
The same generation also sees EJ255/EJ257 Ringland Failure and EJ257 Rod Bearing Failure & STI Rod Knock (2004-2021). Both are documented with symptoms, cost, and a permanent-fix walkthrough — see the full list in the WRX / STI hub.
Cross-check NHTSA campaign 18V-846, which covers FA20 Valve Spring Fracture on 2012-2014 BRZ/Forester XT/WRX/Legacy. Recall work is free at any Subaru dealer — always run your VIN before paying for the fix.
We rate it 5/5 on our DIY scale. Most owners come out ahead with an independent Subaru shop; read labor-hour benchmarks in the repair-costs hub before you commit tools and a weekend.
It's part of our Engine Guides cluster, which collects every article covering the same system as this failure.
Same failure mechanism documented on a different Subaru — shares components with this article.
Same failure mechanism documented on a different Subaru — shares components with this article.
EJ, FA, FB, and EZ boxer deep-dives — the engine background this failure sits inside.
Dig into the Problems Database to plan your next maintenance sprint, or browse every model hub for buyer's guides, generation breakdowns, and known-issue lists.