P0299 on Subaru
Turbo/Supercharger Underboost Condition
P0299 on Subaru vehicles indicates turbo/supercharger underboost condition. Au7o has documented this code across 2 Subaru models — most commonly on Baja, WRX STI. P0299 means the engine computer detected an underboost condition — the turbocharger or supercharger is producing less boost pressure than the PCM expects for the given conditions. The computer compares the manifold/boost pressure sensor reading to a target based on engine load, and when actual boost falls short, it sets this code. The most common real-world cause is a leak somewhere in the intake/charge-air path. You'll typically feel reduced power or sluggish acceleration, and the engine may go into a reduced-power mode. Typical repair costs on Subaru range from $50 to $2,500, depending on the specific model and root cause.
Common Causes of P0299
- •Boost/intake leak (cracked or loose charge-air hose or intercooler)
- •Faulty or sticking turbo wastegate or actuator
- •Stuck or clogged variable-geometry turbo vanes (VGT)
- •Faulty boost pressure or MAP sensor
- •Leaking or disconnected vacuum/boost control lines
- •Restricted air intake or clogged air filter
- •Failed boost control solenoid
- •Worn or failing turbocharger
P0299 on Subaru by Model
Subaru Baja(1 issue)
- Turbo Baja (EJ255) Turbocharger Failure and Banjo Bolt Screen Restriction2004-2006
The Baja Turbo uses the EJ255 turbocharged engine with a TD04 turbocharger. The oil supply banjo bolt that feeds the turbo contains a small mesh screen filter that can clog over time, restricting oil flow to the turbo bearings. Oil starvation causes the turbo to fail prematurely, often with catastrophic results including turbo shaft seizure and oil ingestion into the intake. This is the single most critical maintenance item for turbo Bajas and turbo EJ engines. Additionally, the turbo oil return line can coke and restrict if the engine is shut off immediately after hard driving.
Subaru WRX STI(1 issue)
- Turbo Boost Leak and Wastegate Rattle2004-2021
The VF-series turbochargers on the STI develop boost leaks at intercooler couplers and charge pipe connections, causing inconsistent boost and reduced power. The internal wastegate actuator also develops a characteristic rattle at idle due to worn pivot pins and flapper valve play. While the rattle is mostly cosmetic, boost leaks cause significant power loss and can trigger overboost or underboost codes.
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View P0299 across all makes →Frequently Asked Questions
What does P0299 mean on Subaru?▼
P0299 stands for "Turbo/Supercharger Underboost Condition." P0299 means the engine computer detected an underboost condition — the turbocharger or supercharger is producing less boost pressure than the PCM expects for the given conditions. The computer compares the manifold/boost pressure sensor reading to a target based on engine load, and when actual boost falls short, it sets this code. The most common real-world cause is a leak somewhere in the intake/charge-air path. You'll typically feel reduced power or sluggish acceleration, and the engine may go into a reduced-power mode. On Subaru specifically, this code is documented across 2 models.
What causes P0299 on Subaru vehicles?▼
Common causes on Subaru: Boost/intake leak (cracked or loose charge-air hose or intercooler), Faulty or sticking turbo wastegate or actuator, Stuck or clogged variable-geometry turbo vanes (VGT), Faulty boost pressure or MAP sensor, Leaking or disconnected vacuum/boost control lines. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0299 on a Subaru?▼
Repair costs on Subaru range from $50 to $2,500, depending on the specific model and root cause.
Which Subaru models have P0299 documented?▼
Au7o has documented P0299 on 2 Subaru models: Baja, WRX STI.