Turbocharger/Supercharger A Underboost Condition
What it means
P0299 means the engine isn't producing the boost pressure the ECM expected from the turbocharger or supercharger. The most common cause is a leak in the charge-air plumbing, but a stuck wastegate, faulty boost-control solenoid, or a restricted intake can also be to blame. Expect reduced power until it's fixed.
Can I keep driving? The car will run but feels sluggish and may drop into reduced-power limp mode; you can drive gently to a shop, but avoid hard acceleration until it's fixed.
Real-world scan data
Appears alongside · share of P0299 scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Noticeable loss of power and slow acceleration
- Hesitation or lag under load
- Reduced-power limp mode on hard throttle
Common causes
Most likely first
- Boost leak — split or loose charge-pipe, intercooler hose, or clamp (most common)Likely
- Sticking or worn wastegate or boost-control actuatorCommon
- Faulty boost-control solenoid or vacuum linesCommon
- Restricted intake or exhaust, or a clogged air filterLess often
- Dirty or failing MAF sensor misreporting airflowLess often
- Worn turbocharger or supercharger (bearing, vanes)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and compare commanded vs actual boost to confirm the underboost.
- Pressure- or smoke-test the charge-air system for split hoses and loose clamps between the turbo and intake.
- Check the wastegate/boost-control actuator and solenoid for free movement and proper vacuum, and inspect the control lines.
- Inspect the air filter and intake/exhaust for restrictions; clean or test the MAF sensor.
- Only condemn the turbo itself after leaks and controls are ruled out; clear and road-test.
P0299 by make
Based on commonly reported failure patterns across owner and repair communities, not on our scan data.
BMW
On turbocharged BMWs such as N54 and N55 engines, wastegate actuator problems and split charge pipes are commonly reported causes. These often cause a loss of power in addition to the code.
Chevrolet
On Chevrolet diesel trucks with the Duramax, a sticking variable vane turbo, boost leaks or sensor issues are commonly reported. On small turbo gas engines, look at the charge pipe and wastegate.
Ford
On Ford EcoBoost engines such as the 3.5L, split charge pipes or boots, wastegate problems or a sticking turbo actuator are commonly reported causes. On the 6.7L Power Stroke, the turbo vane mechanism and intake leaks are common suspects.
Ram
On Ram trucks with the 6.7L Cummins, intake leaks, a sticking variable vane turbo or actuator problems are commonly reported causes. Get it checked soon, since reduced power is a problem when towing.
Subaru
On turbocharged Subarus such as the WRX, boost leaks, a stuck wastegate or a failed boost control solenoid are commonly reported causes. Smoke-testing the intake finds boost leaks quickly.
Volkswagen
On VW and Audi turbo engines, a faulty diverter valve, wastegate actuator or a boost hose leak is a commonly reported cause. TDI models can also suffer from a sticking variable vane turbo.
FAQ
Quick answers
Is it safe to drive with P0299?+
Can I just clear P0299?+
Related codes
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