Fault code P0299 – turbocharger/supercharger “A” underboost condition

Fault code P0299 is called “Turbocharger/Supercharger “A” Underboost Condition” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0299

This Diagnostic Trouble Code (DTC) is a generic powertrain code. Error P0299 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly from model to model.

Fault code P0299 – turbocharger/supercharger

This DTC error occurs when the powertrain/engine control module (PCM/ECM) has detected the following. That bank “A”, the turbine or supercharger is not providing the normal boost (pressure) level.

The problem may be caused by various reasons, which will be explained in more detail. On a normally running engine with a turbine or supercharger. The air entering the engine is pressurized, which adds power to the engine.

When this code appears, you will likely notice a decrease in power. Turbochargers are driven by the exhaust gases coming out of the engine. To use the turbine to force air into the intake.

The compressor is mounted on the intake side of the engine and is usually driven by a belt drive. This is done to draw more air into the intake, without a connection to the exhaust.

In Ford vehicles, the ECU checks the Throttle Intake Minimum Pressure (TIP) PID signal while the engine is running. Which indicates the status of the air supply. This code illuminates when the ECU detects that the actual intake pressure through the throttle is less than desired. Normally the data should be below 0.27 bar or more for 5 seconds”.

In the case of VAG vehicles, the code definition is slightly different and means “Supercharging pressure regulation”. That is, the control range is not reached. But, if you understand it, it is just another spelling of this problem.

Symptoms of vehicle malfunctions

The main signal that an error P0299 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will illuminate (the code will be stored as a fault).
  2. Other related fault codes may also be present (e.g. detonation sensor).
  3. Increased engine noise coming from turbocharger flap or hoses.
  4. Reduced engine performance.
  5. Black smoke coming from exhaust pipe.
  6. Contaminated spark plugs.
  7. Elevated engine or transmission temperature.
  8. Increased engine temperature may also cause cylinder detonation.

The severity of code P0299 can range from moderate to severe. If you delay correcting this problem, you may be faced with more significant and costly repairs.

Factors that can cause this error code

The error code P0299 can mean that one or more of the following problems have occurred:

  • Air supply (suction) restriction or leakage.
  • Hoses/hoses not properly connected, disconnected or leaking.
  • Faulty or damaged turbocharger.
  • Possible charge/discharge pressure sensor failure.
  • Failed bypass valve (VW).
  • Low fuel pressure condition (Isuzu).
  • Sticking turbo control solenoid (Isuzu).
  • Defective injector control pressure sensor (ICP) (Ford).
  • Low oil pressure (Ford).
  • EGR system failure (Ford).
  • Variable geometry turbocharger (VGT) drive (Ford).
  • Sticky VGT blades (Ford).

How to fix or reset OBD-2 code P0299

Some suggested steps for troubleshooting and fix the error code P0299:

  1. Check hoses between components.
  2. Check the turbocharger.
  3. Check/clean/replace charge pressure regulator.
  4. Pay attention to proper operation of the bypass valve.

If turbocharger is malfunctioning due to mechanical / internal problems. Or the exhaust system is restricted (usually a clogged catalytic converter). These faults could be the end result of the search.

Diagnose and repair of problems

First, correct the other DTC error codes, if present, before diagnosing the problem associated with the P0299 fault. Next, try to find the Technical Service Bulletins (TSB). Which pertain to your vehicle (year, engine power, model).

TSBs are bulletins issued by the car manufacturer to provide information on known problems. Usually describing specific trouble codes like this one. If there is a known TSB, you should start with the diagnostics described in it, it can save time and money.

Start with a visual inspection. Inspect the air intake system for cracks, loose or disconnected hoses, restrictions, clogs, etc. Repair or replace as necessary.

Check turbocharger solenoid valve operation

If the intake system is OK, you should concentrate your efforts on diagnosing the regulator. As well as the bypass valve, sensors, etc.

There are some known problems on certain makes and engines. For example, a common solution to the P0299 error for VAG is to replace or repair the bypass valve or solenoid valve.

On a GM diesel engine, this code could mean that the resonator of the turbocharger housing has failed. If you have a Ford, you will need to check the damper control valve solenoid for proper operation.

The information in this article is generalized and each model may have its own fix for this code.

On which vehicles does this problem occur most frequently

Fault code P0299 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Acura
  • Audi (A3, A4, A6, Q5, Q7)
  • BMW
  • Chevrolet (Cruze)
  • Citroen (C4, C5, Jumper)
  • Ford (C-Max, Focus, Galaxy, Kuga, Mondeo, S-Max, Transit)
  • Hyundai (Santa Fe, Sonata)
  • Isuzu
  • Jeep (Grand Cherokee, Liberty)
  • Kia (Sorento, Sportage)
  • Land Rover (Evoque, Freelander)
  • Mercedes-Benz (Sprinter, Vito)
  • Mitsubishi (L200, Pajero)
  • Nissan
  • Opel (Astra, Insignia, Meriva, Mokka, Zafira)
  • Peugeot (3008, 307, 308, 408, 508, Boxer)
  • Renault (Duster, Master, Megane, Scenic)
  • Skoda (Octavia, Superb)
  • Toyota (Land Cruiser)
  • Volkswagen (Amarok, Caddy, Crafter, Golf, Jetta, Passat, Tiguan, Touareg, Touran, Transporter)
  • Volvo (S80, V50, XC60, XC70)

Fault code P0299 can sometimes be found with other errors. The most common are the following: P0046, P0152, P0300, P0401, P0471, P2261, P2262.


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