Repair cost
$6,500–$11,000
DIY difficulty
5 / 5
Severity
Critical
Engine, safety, or drivability — fix before driving
Affected
2015-2021
FA20DIT
What goes wrong
Knock control limited by ECU on lower-octane fuel; rod bends, then catastrophic failure.
Symptoms to watch for
- Knock under load
- Loss of power
- Eventual rod knock
Root cause
Aggressive timing tables + 91-octane minimum not always met.
In-article ad
Buy time with these
- • Run only Top-Tier 93 octane; pull timing via tune
Permanent fix
- Long-block replacement; consider stage-1 protective tune.
FAQ
What causes wrx fa20 bent connecting rod?
Aggressive timing tables + 91-octane minimum not always met.
How much does it cost to fix?
National average $6,500–$11,000.
Is this a DIY repair?
Difficulty 5/5. Long-block replacement; consider stage-1 protective tune.
What are the symptoms?
Knock under load; Loss of power; Eventual rod knock
Sources
- • NHTSA
- • Subaru Owner Forums