P0299 Code: Meaning, Causes, Symptoms (& How to Fix it)

The boost pressure is one of the major parts of the engine. It is most commonly used in the turbo engine. It uses to deliver air pressure data and air and fuel ratios in order to regulate engine efficiency. A bad boost pressure sensor leads to engine performance issues. When your powertrain control module (PCM) detects an abnormal reading from the turbo under the boost pressure sensor, it triggers the P0299 code. This article mainly explains the P0299 code symptoms, its causes, and how to fix it.

P0299 Code Definition

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

In the above definition, the underboost term is used for the supercharger or turbocharger that isn’t working properly. In simple terms, your turbocharger or supercharger is not generating sufficient boost according to the requirements.  

What Does Code P0299 Mean?

The P0299 code indicates that your powertrain control module (PCM) detects an abnormal reading from the supercharger or turbocharger under the boost sensor.

P0299 code

Both the supercharger and turbocharger play 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 and supercharger suck gas straight out of the exhaust pipe and transfer it back into the combustor 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.

The PCM looks for a specific range of pressure boosts, and when the PCM detects the low boost, it triggers a P0299 code.

Causes of P0299 Code

  • Bad EGR system
  • Bad supercharger or turbocharger
  • Insufficient oil pressure in the engine
  • Insufficient engine oil
  • Air leak in the intake system
  • Bad boost pressure sensor
  • Exhaust leak
  • Bad PCM
  • Bad MAP sensor
  • Damaged or corroded wiring
  • Bad boost pressure regulation valve

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.
  • Note all the freeze data, which will have information about what conditions the vehicle was under when the code was set.
  • Clear the code and perform a test drive.
  • Visually inspect the turbocharge and supercharger system 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 scan tool to check the boost pressure readings.

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?

  • Repairing or replacing the 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 leak
  • Replacing the bad EGR system
  • 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

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.

How serious is the P0299 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. 

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 possibly 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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