What the OBD-II code p0299 means

Fault code P0299 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0299 – Turbocharger/Supercharger "A" Underboost Condition
P0299
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P0299: causes, symptoms and repairs

The meaning of fault code P0299

P0299 is registered when the supercharger or turbo for car is generating a low or insufficient boost pressure, therefore reducing the engine’s power output. If it does not reach the required pressure level, the vehicle may go into “limp mode”, shutting down the non-essential devices of the car.

Possible causes

  • Low pressure in the lubrication system, causing oil starvation and increased wear.
  • Blockages in the passages of the charger unit, which can occur when carbon deposits form and build up inside the components. This is often a consequence of using the wrong kind of car lubricant or not servicing the boost unit on time. As a result of this, the bearings can be worn down, the turbine component may overheat, and you may see signs of damage at the shaft.
  • A sooty exhaust gas recirculation (EGR) valve can also result in a build-up of carbon deposits, obstructing the VNT mechanism.
  • A clogged air intake system, reducing the effectiveness of the turbocharger.
  • Vacuum actuator failure caused by leaks
  • A faulty injector control or boost pressure sensor
  • A defective wastegate or solenoid failure. The wastegate valve is supposed to remain closed until the correct boost pressure is reached, however, if the regulation solenoid fails, the valve will stay open, stopping the charger from generating the boost.
Symptoms of code P0299

  • A loss of engine power or slow acceleration
  • Activation of the check engine light
  • An unusual or high-pitched sound coming from the engine
  • Activation of the vehicle’s emergency operation mode
  • Black smoke coming from the exhaust
Recommended repairs

  • Check out the related diagnostic trouble codes (DTCs) to identify the possible causes of the error. You can do this by connecting an OBD2 scanner to the vehicle.
  • Examine the condition of the hoses, pipes and vacuum lines linked to the boost unit. You will need to tighten any loose clamps and replace damaged pipe components and seals to prevent or fix leaks.
  • Do a visual inspection of the turbo/supercharger itself to check for cracks, chips, or loose parts, etc.
  • Check whether the sensors are working properly using an appropriate testing tool such as a multimeter. These devices can be replaced at a reasonable price.
  • Make sure that the wastegate is able to move properly and that the boost control solenoid is working. You can test it manually with an air pump or vacuum tester.
  • You may also need to clean the EGR valve and flush out the lubrication system to get the parts to run smoothly again. If the valve is damaged beyond repair, you will need to install a new one.
Frequently Asked Questions (FAQ)

What does the P0299 code mean?


It indicates that the turbocharger/supercharger is not generating enough pressure to boost the engine.

What causes it?


Common causes include charger or solenoid failure, air leaks, low oil pressure, and clogging.

How can I clear this error?


This DTC needs to be followed up with a comprehensive diagnosis in order to determine the exact location of the fault. Once it has been identified and fixed, the DTCs can be reset using the scan tool.

Can I still drive my car or is it too serious?


Due to the effect of the underboost conditions on engine performance, it is better to refrain from driving the vehicle until its fixed. Additionally, if the turbine is broken, parts of the impeller could break off and damage the motor.

Cars the fault code P0299 is most commonly found on

Fault code P0299 - Turbocharger/Supercharger "A" Underboost Condition can occur with any car but is most often found on the following cars:

  • VW: Caddy, Polo, Transporter
  • Ford: Transit, Mondeo, Fiesta
  • Audi: A4, A1, A3
  • Mercedes: Sprinter, W204
  • Mazda: CX5, 6, 3
  • Opel: Astra, Corsa, Insignia

If you get the code P0299 on your car, make sure that the diagnostics are carried out correctly and the error is still relevant. Check for symptoms associated with the problem and explore options for resolving it.

What to do if the fault code p 0299 appears

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