P0299 — Turbocharger / supercharger underboost
The computer commanded boost and didn’t see enough — leaks, wastegate/vane issues, or sensor problems are typical on turbo cars.
What it means in plain English
P0299 means underboost: actual boost is below target. On turbocharged engines this can be a boost leak (hoses/intercooler), wastegate or vane actuator problem, restricted air path, or sensor/control faults. Power feels flat.
Common causes
- Boost leaks (hoses, clamps, intercooler)
- Wastegate / vanes stuck or actuator faults
- Dirty intake path; failed diverter/bypass valve (design-dependent)
- Boost / MAP sensor issues
What you can safely check
- Inspect visible boost hoses for oil film and cracked rubber after the turbo.
- Note whether limp mode or overheating accompanies the code.
Pull the code yourself (disclosed)
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A reusable Bluetooth OBD-II scanner lets you read the code and freeze-frame data before authorizing “mystery” diagnostics. One option: BlueDriver Bluetooth Pro OBD-II scan tool (BlueDriver/Levanta affiliate). Any capable OBD-II reader is fine — this is not required to use Fair Auto Shops.
When to go to a shop
Boost-leak smoke tests and actuator checks beat replacing a turbo on day one. Ask what pressure tests were done before a turbo assembly quote.
Typical related repair costs
Underboost repairs range from a clamp/hose to a turbocharger assembly. We omit a single national average because the failed part isn’t determined by the code alone.
Questions to ask before you authorize work
Use questions before you authorize a repair and how to read a repair estimate. Watch for patterns in spotting upselling.
Find an honest independent shop
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FAQ
What should I do first with a P0299 code?
Photograph all codes, note symptoms and whether the light is flashing, avoid clearing data until a shop sees it, then use an independent shop with a clear diagnostic plan.
More check-engine codes
P0420 · P0430 · P0300 · P0301 · P0171 · P0174 · P0455 · P0456 · P0442 · P0446 · P0128 · P0401 · P0133 · P0113 · P0506 · P0507 · P0700 · P0741 · P0011 · P0325 · P0340 · P0335 · P0101 · P0135 · P0440 · P0441 · P0010 · P0500 · P0121
Hub: How to read a check-engine code · Repair cost guides · Affiliate disclosure