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P0299 OBD-II Trouble Code: Turbo / Supercharger Underboost Condition

Check Engine Light

P0299 code definition

P0299 is a generic OBD-II diagnostic trouble code indicating an underboost condition.

What the P0299 code means

The P0299 code indicates that the Turbo or Supercharger "A" has excessively low output. The ECU looks for a specific range of boost and when the low boost is detected by the ECU, it sets a P0299 code.

This code will illuminate a Check Engine Light on the dashboard and may put the vehicle in limp mode. The limp mode is to prevent further damage to the vehicle and will remain until the code is cleared or repaired.

What causes the P0299 code?

  • Faulty turbo or supercharger
  • Low oil pressure in the engine
  • Fault in the EGR system
  • Air or intake leak or restriction
  • Faulty boost pressure sensor

What are the symptoms of the P0299 code?

  • Check Engine Light is illuminated
  • Some vehicles may go into a limp mode
  • Lack of engine power
  • Mechanical noise (failing turbo / supercharger)

How does a mechanic diagnose the P0299 code?

  • A mechanic will begin by hooking up a scan tool into the vehicle's OBD-II port and checking for any codes present.

  • The technician will note all freeze frame data, which will have information about what conditions the vehicle was under when the code was set.

  • The codes will then be cleared and a test drive performed.

  • Next, a visual inspection will be performed of the turbo / supercharger system, intake system, EGR system, and any other associated systems.

  • After, the scan tools will used to check for proper boost pressure readings.

  • All mechanical systems will be inspected such as the turbo or supercharger itself, oil pressure and the intake system for leaks or restrictions.

Common mistakes when diagnosing the P0299 code

Mistakes can be made if all steps are not followed in the proper order are are not completed at all. P0299 can have a wide variety of symptoms and causes. Following the diagnostic steps properly and in the right order is important for accurate diagnosis.

How serious is the P0299 code?

The presence of the P0299 code can point to some rather serious mechanical failures, especially if left unaddressed. If any mechanical noise or drivability concerns are present, then the vehicle should be repaired as soon as possible. If a turbo charger unit fails and the vehicle is driven it can result in costly engine damage.

What repairs can fix the P0299 code?

  • Turbo or supercharger replacement
  • Repairing of the intake system
  • EGR replacement
  • Boost pressure sensor replacement
  • Low engine oil pressure repair

Additional comments for consideration regarding the P0299 code

When a turbocharger fails it can cause a piece of the turbine to become sucked into the engine. If a sudden loss of power is observed along with a mechanical noise stop the vehicle in a safe location immediately.

Need help with a P0299 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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