OBD codes / P0299
P0299
SeriousTurbocharger/Supercharger Underboost Condition
Usually drivable, gently. Most cars respond to P0299 with limp mode — down on power but safe to operate — so you can typically drive to a shop without drama. Avoid heavy throttle and highway passing until it's diagnosed: if the cause is a failing turbo, hard use can finish it off and send debris through the engine. If you hear grinding from the turbo or see blue smoke, stop driving and have it towed.
What this code means
A turbocharged (or supercharged) engine's computer commands a target boost pressure and watches the boost sensor to confirm it arrives. P0299 sets when measured boost stays meaningfully below that target — the engine is asking for boost and not getting it. The most common real-world cause is a leak in the pressurized plumbing between the turbo and engine: a split intercooler hose, a loose clamp, a cracked charge pipe, or a leaking intercooler, all of which let boost escape before the engine sees it. Other causes include a wastegate stuck open (bleeding off boost it should be holding), a sticking variable-geometry (VGT) actuator or carboned-up vanes on diesels, a restricted air intake or clogged filter, a faulty boost-control solenoid, an exhaust restriction, or a genuinely worn turbo with damaged bearings or blades. Most vehicles respond with limp mode — power is limited to protect the engine — so the car feels dramatically slower even though it usually remains drivable. Because causes range from a loose clamp to a failed turbocharger, a boost-leak test is the smart first diagnostic step before any expensive parts are discussed.
Symptoms you might notice
- Noticeable loss of power, especially under acceleration or uphill
- Reduced-power (limp) mode that may reset after a key cycle
- Hissing or whooshing sound under boost (a leak talking)
- Slower, lazier throttle response
- Worse fuel economy
- Whining or grinding turbo noises if the turbo itself is failing
What it costs to fix
Varies by vehicle — get it diagnosed.
The repair cost for this code depends too much on your exact vehicle and the underlying cause to quote a meaningful range. Confirm the cause first so you only pay for the fix you actually need.
Diagnose P0299 for my vehicle →Frequently asked
What does P0299 mean and why is my car so slow?
The computer commanded boost and measured less than it asked for, so it set P0299 and, on most vehicles, limited power to protect the engine — that limp mode is why the car suddenly feels gutless. The boost itself is usually escaping through a leak or being lost to a control or turbo fault.
What's the most common cause of P0299?
A boost leak — a split intercooler hose, loose clamp, or cracked charge pipe letting pressurized air escape before it reaches the engine. That's why a boost-leak pressure test is the standard first step. Wastegate and VGT actuator faults are next in line, with an actual worn-out turbo further down the list than most people fear.
Does P0299 mean I need a new turbo?
Not usually. Plenty of P0299s are fixed with a hose, a clamp, an actuator, or a cleaning of stuck VGT vanes on diesels. The turbo itself is the last suspect, condemned only after the plumbing pressure-tests tight and the controls check out — so be wary of any diagnosis that jumps straight to turbo replacement.
How much does P0299 cost to fix?
The spread is unusually wide, which is why we don't pretend there's one number: a clamp or hose is a cheap fix, an actuator or boost solenoid is moderate, and a replacement turbocharger is a major repair. Paying for a proper boost-leak test first is the best money you can spend on this code.
Is it safe to keep driving in limp mode with P0299?
For a reasonable trip to a shop, generally yes — limp mode exists precisely to make the car safe to move while protecting the engine. Keep throttle light and avoid situations that need quick acceleration. Grinding noises, heavy smoke, or oil consumption change the answer to no; those point at turbo hardware failure.
Seeing P0299 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0299 for my vehicleSymptoms that trigger P0299
Drivers who get this code often notice one of these — each has its own likely-causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0299 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.