What does it mean?
When a P0299 code is exhibited in an OBD-II equipped vehicle, it indicates that the powertrain control module (PCM) has detected a turbocharger or supercharger low boost condition. This code may be caused by either a mechanical or an electrical malfunction in the forced air induction (FAI) system. Both the turbocharger and the supercharger are forced air induction systems that are used to increase engine performance.
Ambient air is drawn into each type of device, which then compresses the air and forces it into the engine combustion chambers. The primary difference in the turbocharger and supercharger is the method in which they are driven. The turbocharger is driven by engine exhaust as it escapes the manifold. The supercharger is driven by a belt that runs off the engine crankshaft. FAI systems typically use some type of intercooler to make the air that is introduced to the engine even cooler and denser.
The boost controller is sometimes a stand-alone module but more often it is an integrated part of the PCM. Input data from various engine and transmission sensors is used (by the controller) to determine how much boost pressure is required for the engine to perform at optimum levels. Actual boost pressure is then monitored to determine whether or not it meets desired levels.
The PCM compares actual boost pressure with the desired boost pressure and initiates bypass control valves and/or blow-off valves as needed. Various bypass control valves and pressure relief valves are used to regulate boost pressure. Most are actuated with electronically but there are a few manufacturers that still use a vacuum operated design.
Consult a reliable vehicle information source (such as a professional technical data service) for forced air induction control system specifications (for your vehicle) prior to attempting a diagnosis. The engine drivability and engine lubrication system must be in good working order before attempting to diagnose this code. If the PCM detects a level of boost pressure that is lower than the programmed limit, a code P0299 will be stored and a malfunction indicator lamp (MIL) may be illuminated.