P0299
Turbocharger/Supercharger A Underboost ConditionP0299 is a generic OBD-II powertrain diagnostic trouble code: Turbocharger/Supercharger A Underboost Condition. It is logged by the engine control unit when the turbo/boost monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0299 means
Diagnostic trouble code P0299 indicates that the engine control module has detected a turbocharger or supercharger underboost condition on bank A. In other words, the actual intake manifold boost pressure measured by the boost/MAP sensor is staying below the target value the ECU is commanding for the current engine load and RPM, for longer than the diagnostic monitor allows.
Because boost is essential to a modern forced-induction engine's torque output, the ECU typically responds by illuminating the check engine light and pulling timing, fuel and/or boost so the vehicle enters a reduced-power or limp mode until the fault is cleared. The code itself is generic SAE and applies to most petrol and diesel vehicles fitted with a turbocharger or supercharger, although the exact monitoring strategy and threshold values are manufacturer-specific.
P0299 is a symptom code rather than a root-cause code, so the underlying fault can range from a simple cracked intake hose or stuck wastegate to a worn turbo, a bad boost pressure sensor, or even a software/calibration issue. A proper diagnosis requires comparing commanded boost against actual boost on a scan tool while road-testing the vehicle.
Common causes
Most-frequently reported root causes when P0299 is logged.
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1
Leaking, cracked, collapsed or disconnected intake/boost hose or intercooler pipe between the turbo and the throttle body.
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2
Stuck-open wastegate, faulty wastegate actuator, or a leaking boost-control solenoid.
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3
Faulty or contaminated boost pressure (MAP) sensor reporting low boost.
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4
Worn or mechanically damaged turbocharger or supercharger (worn bearings, damaged vanes, oil-fouled compressor).
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5
Stuck or sticking variable geometry turbo (VGT/VNT) vanes due to soot buildup.
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6
Restricted air intake or clogged air filter limiting airflow into the turbo.
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7
Restricted or damaged intercooler reducing charge-air flow.
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8
Wiring or connector faults to the boost sensor, boost solenoid, or wastegate actuator.
Symptoms drivers notice
How to diagnose P0299
A typical diagnostic flow when this code is present.
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1
Connect a scan tool, record all stored and pending codes, and note any related freeze-frame data before clearing anything.
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2
Visually inspect the entire charge-air system for split, popped-off or oil-soaked intake hoses, loose clamps and damaged intercooler pipes.
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3
Check the air filter and intake tract for restriction, and inspect the boost sensor and its connector for damage or contamination.
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4
Use live data to compare commanded boost vs. actual boost during a controlled road test, looking for where the two diverge.
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5
Test the wastegate actuator and boost-control solenoid for correct mechanical movement and electrical operation.
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6
On VGT/VNT diesels, check vane operation and look for sticking caused by soot or carbon buildup.
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7
If the charge-air system and sensors test good, inspect the turbocharger itself for shaft play, oil leakage and damaged compressor/turbine wheels.
Vehicles where we've handled P0299
Platforms in our catalogue with confirmed P0299 coverage.
Related powertrain codes
- P003A — Turbocharger/Supercharger Boost Control A Position Exceeded Learning Limit
- P003B — Turbocharger/Supercharger Boost Control B Position Exceeded Learning Limit
- P0045 — Turbocharger/Supercharger Boost Control A Circuit/Open
- P0046 — Turbocharger/Supercharger Boost Control A Circuit Range/Performance
- P0047 — Turbocharger/Supercharger Boost Control A Circuit Low
- P0048 — Turbocharger/Supercharger Boost Control A Circuit High
Frequently asked questions
Is it safe to drive with a P0299 code?
You can usually drive the vehicle home or to a workshop, but you should avoid hard acceleration and heavy loads. Continued driving with an unresolved underboost condition can mask a failing turbo or worsen related faults, so it should be diagnosed promptly.
Will P0299 always put the car into limp mode?
Not always, but it is very common. Many manufacturers reduce engine torque or limit boost as soon as P0299 becomes a confirmed fault to protect the engine and turbocharger, which is felt as a sudden loss of power.
Can a boost leak alone trigger P0299?
Yes. A split intercooler hose, popped-off boost pipe or failed clamp is one of the most common causes, because the ECU sees commanded boost but the sensor reports a much lower actual value. A pressurized smoke test of the charge-air system is the fastest way to find such leaks.
Does clearing the code fix the problem?
No. Clearing P0299 only resets the warning light. If the underlying cause (leak, stuck wastegate, failing turbo, bad sensor, etc.) is still present, the code will return, usually within one or two drive cycles under load.
Disabling P0299 in software
RaceTune can permanently disable P0299 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P0299 disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C50 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0299 in your scan?
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