OBD / DTC guide

P0299

Turbocharger / Supercharger Underboost

P0299 means boost pressure is below what the control system expects. Drivers often notice loss of power, especially under load. Boost leaks, intercooler/hose issues, wastegate/actuator behavior, and sensor plausibility are common themes. The code is not a guaranteed turbo replacement.

Related symptoms

The same code can show up with different feelings behind the wheel. These links go to general symptom guides—pairing symptoms with context usually beats guessing from the code alone.

Loss of powerTypical under load when boost should build.Check engine lightOften present—note companion codes.Turbo-related noiseSometimes discussed with leaks.Engine misfirePossible when boost/mixture swings.Black smokeSome diesel/gas scenarios.

All symptoms

Common root-cause themes

Priority changes by vehicle platform. Treat this as orientation, not a workshop verdict—confirm with testing for your car.

Often discussed pattern
Charge-air leaks: loose clamps, cracked hoses, intercooler issues.
Common in some setups
Wastegate/actuator not achieving target boost.
Common in some setups
Turbo mechanical wear—should not be assumed without supporting tests.
Common in some setups
MAP/MAF inconsistencies affecting boost estimation.

Risk and urgency

Urgency: higher — take care

Major power loss, metallic turbo noise, or strong overheating warnings should reduce how hard you push the engine until it is assessed.

Sensible first checks

Inspect boost hoses and clamps for oil mist, cracks, and looseness (engine cool/safe).
Scan for related turbo/boost codes together—not in isolation.
Note whether the problem is load-dependent.
Live data review (requested vs actual boost) helps when available.
Use the guided flow to capture driving context and warnings.

Related parts (context)

Use these pages for background. A parts swap without confirmation can be expensive if the root cause is elsewhere.

Turbo MAP sensor Intercooler hose

Parts hub

Interpret the code with real-world context

In the guided flow, combine the code with how the car feels, when it happens, and any other codes stored alongside it.

Start diagnosis All fault codes

P0299 fault code — more context

P0299 is one of the most searched turbo codes. The internet often jumps to turbo replacement; the workshop frequently starts with leak checks and control diagnostics.

Treat this page as orientation: combine codes, symptoms, and measured data for your specific vehicle.