P0299 Code Meaning, Causes, Symptoms, And How to Fix

The engine of your vehicle most commonly depends on the downward motion of its piston to generate a vacuum, essential for pulling in the air-fuel mixture. However, supercharged or turbocharged engines utilize a forced-induction mechanism to suck in extra air. The P0299 code indicates an issue with the turbo/supercharger.


When a supercharger or turbocharger functions properly, it pressurizes the air directed to the engine. This feature enables it to generate more power despite its size. But when the turbocharger or supercharger produces lower output than the requirements, the powertrain control module (PCM) of your vehicle triggers the P0299 engine code. This code indicates that your turbocharger is not compressing the air according to the requirements.

P0299 Code Definition

P0299 code stands for “Turbocharger/Supercharger “A” Underboost Condition.”

What Does Code P0299 Mean?

The P0299 code indicates that your PCM/ECM detects that supercharger or turbocharger “A” has excessively low output. This code is triggered when the low boost pressure is detected.

P0299 code

The supercharger or turbocharger plays a vital role in ensuring the efficient working of the engine. If your turbocharger or supercharger has a problem, you should fix it as soon as possible.  

Your vehicle’s turbocharger/supercharger sucks gas straight out of the exhaust pipe and transfers it back into the combustion chamber with high pressure. This process improves the amount of O2 in the air-fuel mixture reaction and adds ignitable gases from the exhaust to the air-fuel mixture. This precarious combination improves engine power and performance.

A bad supercharger or turbocharger may lead to engine problems such as poor fuel economy, poor performance, and even engine damage.

When your PCM detects the low boost pressure, it triggers the P0299 engine code.

Causes of P0299 Code

A vehicle usually triggers the P0299 code due to one or more of the following reasons:

  • Bad EGR system
  • Bad supercharger or turbocharger
  • Low oil pressure
  • Insufficient engine oil
  • Air leak in the intake system
  • Bad boost pressure sensor
  • Exhaust leaks
  • Bad PCM
  • Bad MAP sensor
  • Damaged or corroded wiring
  • Faulty turbo pressure regulator or wastegate

Symptoms of P0299 Code

  • Check engine light illuminates
  • Limp mode
  • A reduction in engine power
  • Poor fuel economy
  • Poor acceleration
  • The turbocharger or supercharger is generating more noise than usual

Read More: P0121 Code Symptoms and Causes

How to diagnose the P0299 Code?

You must have the following tools to diagnose the P0299 code:

  1. OBD-II scanner
  2. Turbocharger Rebuild Kit
  3. Exhaust Back Pressure Gauge

Follow the below-given steps to diagnose the P0299 code:

  • Use an OBD-II scanner to scan the P0299 code. Analyze the data stored in the ECM/PCM memory to find the main issue.
  • Clear the stored codes and perform a test drive. If the code returns, perform a deep inspection.
  • Visually inspect the turbocharge or supercharger system of your car for damage. If there is any damage, fix it.
  • Make sure that the turbocharger or supercharger is installed correctly.
  • Inspect the intake system for leaks.
  • Inspect the EGR system. If any part of the EGR system is bad, replace it.
  • Inspect the exhaust system for a leak. If there is any leak, repair it.
  • Use a scanner to check the boost pressure readings.
  • Test the boost pressure sensor by using a scan tool.
  • After making the necessary repairs, clear the codes and perform a test drive.

Common P0299 Code Diagnostic Mistakes

  • Not managing a visual inspection first
  • Not properly inspecting all the parts
  • Replacing the needless parts
  • Not inspecting the fuel system for a leak before replacing the boost pressure sensor.
  • Not checking the engine oil level before replacing other parts
  • Not inspecting the system for vacuum leaks
  • Not clearing the PCM codes after fixing the codes

What repairs can fix the P0299 Code?

One or more of the following repairs can fix the P0299 code:

  • Repairing or replacing the faulty supercharger or turbocharger.
  • If your engine oil is low, then add more
  • Fixing the intake leak
  • Replacing the bad boost pressure sensor
  • Fixing the exhaust leaks
  • Replacing the bad EGR system
  • Repairing the boost pipe leak
  • Fixing the cause of low engine oil pressure

Repair Cost of P0299 Code

The repair cost of the trouble code P2099 varies according to labor cost, the vehicle model, and your area. To fix the P0299, you may need one or more of the following repairs:

Vacuum leak repair$70 to $380
Repair exhaust leak$90 to $210
MAP sensor replacement$50 to $180
Turbocharger assembly replacement$1,880 and $2,180
Boost sensor replacement$170 to $210

How serious is the P0299 Engine Code?

The P0299 code is considered a serious trouble code. This code generates different drivability issues, such as poor fuel economy, poor engine power, or limp mode. When your vehicle goes into limp mode, you can’t drive your vehicle or can drive for a very short distance. Therefore, it is recommended to fix this code as soon as possible. 

FAQ Section

Can you drive with a P0299 Code?

Driving the car with the P0299 code for a long distance is not recommended. As you notice this code, you should drive your car to the nearest workshop to fix it. This code generates different problems which make the vehicle hard to drive.

Can a dirty air filter cause a P0299 Code?

Yes, a dirty air filter is one of the common causes of the P0299 code. When your vehicle’s air filter is clogged, it restricts airflow to the turbo, causing the engine to run at less speed than normal. This forces the PCM to trigger the P0299 code. To stop this issue, continuously inspect your filter and replace it if needed.

What can cause Turbo Underboost?

  • Leaking or damaged charge piping
  • Failed diverter valve
  • Failed boost pressure regulation valve
  • Failed turbocharger or supercharger
  • Faulty boost pressure sensor
  • Faulty wastegate/wastegate actuator
  • Bad MAP sensor

What are the symptoms of a bad turbocharger?

  • Check engine light illumination.
  • Poor fuel economy
  • Poor engine performance
  • Poor acceleration
  • Excessive smoke from the exhaust pipe
  • Siren noise
  • Blue or black exhaust smoke

Can you drive a car if the turbo goes out?

The vehicle can run with a bad turbocharger, but it will perform poorly, and your decision could have dramatic repercussions.

Can an exhaust leak cause P0299?

The exhaust leak is one of the major causes of the P0299 code.

How far can you drive with a blown turbo?

You must continuously check your engine oil level if you decide to drive on a blown turbocharge and don’t go more than 100 miles.

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