P0299: the turbo or supercharger isn't building enough boost
Boost is the extra air pressure a turbocharger or supercharger pushes into the engine on top of what it would breathe in on its own, and the engine control unit expects a certain amount for a given demand from the accelerator. This code means the actual boost pressure has stayed below that expected amount for long enough that the computer no longer treats it as a passing dip. It doesn't say why the boost is low, only that it is.
You might notice
- The engine feels noticeably down on power, especially under acceleration
- The engine warning light comes on
- boost
- — the extra air pressure a turbocharger or supercharger pushes into the engine
What the code itself says
P0299 is a powertrain (engine, gearbox and drive system) code, and the 0 after the letter means it is a generic code with a standard meaning.
Grouped here as: Engine running, fuelling and misfires — Air metering, fuelling, ignition, misfire, idle, boost, knock, oxygen sensors and the catalyst, all working together in the running engine. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
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