P0299 on Porsche
Turbo/Supercharger Underboost Condition
P0299 on Porsche vehicles indicates turbo/supercharger underboost condition. Au7o has documented this code across 1 Porsche model — most commonly on 718 Cayman. 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 Porsche range from $2,500 to $6,000, 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 Porsche by Model
Porsche 718 Cayman(1 issue)
- 2.0L Turbo Wastegate Actuator Seizure Causing Boost Collapse / Limp Mode2017-2025
On the base 2.0L 718 the single turbocharger and its electronic wastegate actuator are mounted low under the belly pan, exposing the actuator to road water, salt, and debris. Over time the actuator rod corrodes and seizes, so boost builds momentarily (e.g., ~15 psi) then collapses, or never exceeds ~5 psi. The result is sudden loss of power, juddery delivery under hard acceleration, and sometimes a PSM/engine warning; restarting the engine often temporarily restores boost. The 2.5L is less affected because its turbo sits higher in the engine bay. Porsche's official remedy for a failed actuator is replacement of the complete turbocharger; later parts have improved weather protection. This is distinct from the audible idle wastegate rattle in that it produces actual boost loss and turbo replacement.
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View P0299 across all makes →Frequently Asked Questions
What does P0299 mean on Porsche?▼
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 Porsche specifically, this code is documented across 1 model.
What causes P0299 on Porsche vehicles?▼
Common causes on Porsche: 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 Porsche?▼
Repair costs on Porsche range from $2,500 to $6,000, depending on the specific model and root cause.
Which Porsche models have P0299 documented?▼
Au7o has documented P0299 on 1 Porsche model: 718 Cayman.