P0299 on Mazda
Turbo/Supercharger Underboost Condition
P0299 on Mazda vehicles indicates turbo/supercharger underboost condition. Au7o has documented this code across 4 Mazda models — most commonly on CX-50, CX-7, Mazdaspeed3. 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 Mazda range from $150 to $3,000, 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 Mazda by Model
Mazda CX-50(1 issue)
- Turbo Wastegate Rattle on Cold Start2023-2025
The turbocharger wastegate actuator rattles audibly on cold start and during warm-up on the 2.5T engine. The wastegate flapper has slight play in its pivot, causing a metallic rattle until exhaust gas pressure and temperature stabilize. Mazda has acknowledged this as a characteristic of the turbo design but some cases involve excessive wear.
Mazda CX-7(1 issue)
- 2.3L Turbo VVT Actuator and Turbocharger Failure2007-2012
The CX-7's 2.3L DISI turbocharged engine (shared with the Mazdaspeed3) suffers from VVT actuator failure and premature turbocharger wear. Carbon buildup on the direct-injection intake valves compounds the issue. Extended oil change intervals accelerate turbo bearing wear.
Mazda Mazdaspeed3(2 issues)
- K04 Turbocharger Failure and Boost Leaks2007-2013
The Mazdaspeed3's K04 turbocharger has a high failure rate, estimated at 30% or more among forum users, especially on modified vehicles. Turbo failures can be catastrophic, with turbine fragments entering the engine and destroying the block. The turbo oil feed line is also a known failure point — the O-ring gasket behind a crimp connection deteriorates from heat exposure, causing oil leaks that are both a fire hazard and turbo oil starvation risk. Additionally, boost leaks from aged intercooler piping and cracked vacuum lines are common.
- Turbocharger Seal Failure and Oil Burning2007-2013
The Mazdaspeed3's K04 turbocharger develops seal failures from the same oil starvation issue affecting the CX-7 and Mazdaspeed6. The turbo oil feed banjo bolt screen clogs with carbon, starving the turbo bearing of oil. The bearing wears, allowing oil to pass through the compressor and turbine seals into the intake and exhaust. This causes blue smoke, oil consumption, and eventual turbo failure.
Mazda Mazdaspeed6(2 issues)
- Turbocharger Oil Feed Line Leak and Turbo Failure2006-2007
The Mazdaspeed6 shares the K04 turbocharger and its associated problems with the Mazdaspeed3. The turbo oil feed line uses an O-ring gasket behind a crimp connection that sits directly against the turbo's hot side. The O-ring degrades from heat exposure, causing oil to leak onto the exhaust manifold — a fire hazard. Turbo failures are accelerated by the oil starvation that follows, and the PCV system contributes additional oil contamination to the turbo bearings. Mazda extended warranty coverage for smoking turbos under a Special Service Program.
- Turbocharger Oil Starvation and Failure2006-2007
The Mazdaspeed6 shares the 2.3L DISI turbo engine with the Mazdaspeed3 and CX-7, inheriting the same turbo oil starvation issue. The turbo oil feed line's banjo bolt contains a small mesh screen that clogs with carbon deposits, restricting oil flow to the turbo bearing. The K04 turbocharger fails between 50,000-100,000 miles if the screen is not maintained. The AWD system adds additional drivetrain stress.
Looking for P0299 on a different make?
View P0299 across all makes →Frequently Asked Questions
What does P0299 mean on Mazda?▼
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 Mazda specifically, this code is documented across 4 models.
What causes P0299 on Mazda vehicles?▼
Common causes on Mazda: 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 Mazda?▼
Repair costs on Mazda range from $150 to $3,000, depending on the specific model and root cause.
Which Mazda models have P0299 documented?▼
Au7o has documented P0299 on 4 Mazda models: CX-50, CX-7, Mazdaspeed3, Mazdaspeed6.