P0299 – Turbocharger/Supercharger “A” Underboost Condition

The trouble code P0299 indicates that your vehicle’s turbo or supercharging system is creating an underboost condition. Generally, problems in your turbo/supercharger system should be taken seriously and repaired as soon as possible to prevent more serious and expensive engine damage. If you are experiencing a P0299, continue reading to learn more.

P0299 Definition

P0299 VW/Audi Definition: Boost Pressure Regulation, Control Range Not Reached

P0299 Ford Definition: Turbo/Supercharger Underboost Condition

P0299 Chevy Definition: Turbo/Supercharger Underboost Condition

If you want to learn about the P0299 OBD2 code, this is the right place
Here’s where you can get a thorough understanding of the P0299 OBD2 code

What Does P0299 Mean?

On vehicles equipped with a turbo or supercharger, air entering the engine is compressed and generally cooled before entering the intake manifold. This feature allows the engine to create substantially more power than engines without turbo or superchargers. When you experience a P0299 trouble code, the ECM has determined that your forced induction system is not producing enough boost.

As the vehicle is working, incoming air is compressed and then forced into the intake manifold. This pressurized air is called a “boost” and is monitored and regulated by the PCM. The boost the PCM allows the turbo/supercharger to create varies due to different operating conditions and driver inputs. The PCM compares the amount of the desired boost to the amount of the actual boost. If the actual boost cannot reach the desired level, the check engine light will be illuminated, and the car may enter “limp mode.”

When our forced induction system is not producing enough boost, th ECM triggers P0299 code
The P0299 code means the ECM has determined that your forced induction system is not producing enough boost.

What Are The Symptoms Of The P0299 Code?

The P0299 code will usually be accompanied by a few noticeable symptoms that include:

  • Activation of the check engine light
  • Low engine power
  • Unusual engine noises
  • Black smoke from the exhaust

What Are The Causes of P0299?

  • Failed turbo or supercharger
  • Intake air/book leak
  • Vacuum leak
  • MAP or boost pressure sensor failure
  • Turbocharger wastegate and/or solenoid failure

How Serious Is The P0299 Code?

P0299 is a serious code. Failure to properly diagnose and repair the air induction system on a turbo or supercharged vehicle can potentially result in severe and expensive engine damage. It is common for a turbocharger to fail internally and cause scraps of metal to be introduced into the engine.

How To Diagnose And Fix The P0299 Code

the steps To Diagnose And Fix The P0299 Code
8 steps to diagnose and fix the P0299 code

Diagnosing a P0299 can vary widely from make to make, so consulting a service manual with vehicle specific information is highly recommended. But here are some general guidelines to follow.

  1. Scan the vehicle with a scan tool and record all codes and freeze frame data. If there are any other codes related to engine performance, including EGR, repair them first.
  2. Next, perform a thorough visual inspection of all boost piping and hoses, air intake system, and vacuum lines. Make sure all clamps are tight and properly positioned. If any leaks are found, repair or replace the component.
  3. If no leaks are visible, it may be necessary to use a smoke machine or introduce low pressure compressed air into the intake system to check for leaks.
  4. Once you have verified there are no leaks, remove the pipe from the turbo’s outlet side and look at the wheel/shaft for excessive side to side or up and down movement. Ensure the turbo has had time to cool off before touching, as it gets very, very hot during normal operation. If there are any signs of damage, you should replace the turbo.
  5. Use a scan tool to compare MAP sensor readings at idle and at 2500RPM with the specifications in-service information.
  6. If equipped with a Mass Air Flow sensor, perform the same test as the MAP sensor.
  7. Certain cars come equipped with a boost sensor that should also be tested using the correct service information. If any of these are out of specification, replace them.
  8. Check to make sure that the wastegate of capable of moving and is not seized in place. These are typically vacuum or electronically controlled. Again, consult service information. If it is vacuum controlled, ensure that the control solenoid has a steady vacuum with the engine running. Use a scan tool to perform a functional test of the vacuum solenoid to verify that the solenoid can open and close and the PCM is capable of controlling it.

Please use the above steps as a general guideline for diagnosis. The forced induction systems used by different vehicles make dramatic differences, so it would be impossible to cover each vehicle specific test in the space provided.

Common Mistakes To Avoid While Diagnosing The P0299 Code

Remember to check the engine air filter, and a dirty filter could not allow enough air into the intake system, causing a low boost condition. Also, on some cars, a fault in the EGR system can cause P0299, so repair EGR issues first. And, remember, just because you can’t see a leaking air pipe or hose with the engine off doesn’t mean it isn’t leaking under boost pressures.

Tips To Avoid P0299 In The Future

As usual, proper maintenance is key! Make sure to change your oil using the appropriate oil viscosity and specifications. The engine oil also lubricates your turbo/supercharger, so this is very important. Please do your best to keep rodents out of your engine bay, as they tend to destroy vacuum lines and electrical wires. And before shutting off your car, let it idle for a minute or two to allow the turbo to cool before cutting off its oil supply when shutting down the engine.

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