Boost leaks at the intercooler or its connections are common issues on the 2020 Subaru WRX, causing code P0299 and noticeable power loss. The top-mount intercooler design has specific leak points that WRX owners should know about.
WRX Intercooler System
The WRX uses a top-mount intercooler (TMIC) that sits on top of the engine under the hood scoop. Pressurized air from the turbo enters through a Y-pipe, passes through the intercooler, and exits to the throttle body. Each connection point is a potential leak location.
Common WRX Boost Leak Points
The intercooler inlet and outlet couplings can loosen or crack. The Y-pipe has multiple connections that can fail. The intercooler end tanks can develop cracks from heat cycling. The turbo outlet connection to the Y-pipe is under stress. Clamps can loosen from vibration.
Symptoms of Intercooler Boost Leak
Noticeable power loss, especially at higher RPM where boost should be highest. P0299 underboost code. Audible hissing under boost (if leak is large enough). Slower turbo response as pressure escapes. The turbo works harder for less result.
Finding Boost Leaks
Smoke testing is most effective - pressurized smoke shows exactly where it escapes. Soapy water sprayed on connections shows bubbles at leaks. Pressurize the system with boost tester and listen for leaks. Visual inspection catches obvious cracks or disconnections.