Home / OBD Codes / P0239 OBD-II Trouble Code: A Malfunction on the Circuit of Turbocharger Boost Sensor B

P0239 OBD-II Trouble Code: A Malfunction on the Circuit of Turbocharger Boost Sensor B

The Definition of Code P0239

A Malfunction on the Circuit of Turbocharger Boost Sensor B

The Meaning of Code P0239

P0239 is a trouble code that will be triggered when your engine control module is detecting an input malfunction in the boost pressure sensor B. This code will appear when there is a difference in the pressure reading on the ECM compared to the reading on the MAP, especially when the engine is not running. The pressure level of the boost sensor should be zero.

While the code P0239 is similar in nature to the trouble code P0239, you should never assume that the causes and symptoms are the same. Different vehicles will have different conditions on why this code can appear.

Be informed that the appearance of OBD trouble codes does not mean that there is a specific problem with a specific component of your vehicle. But the appearance of these codes means that the mechanics will be able to search for possible causes inside the engine. The real causes might include multiple sources.

Regarding the code P0239, the vehicles that show this code will usually point to a singular reason. The reason is a difference in the reading from the ECM and the sensor on the boost pressure. The percentage of difference should always be inside the acceptable variance of value. If they are outside the close limits, then the code will appear.

The Effect of Turbocharging on Increasing Vehicle’s Performance

P0239 OBD II Trouble Code
Turbochargers can give extra power to your engine because it forces a lot more air into the fuel mixture compared to the normal engine condition. The higher air volume in the cylinder will contribute to increased power from the fuel combustion process.

On engines that are designed specifically for turbocharging mechanisms, the turbochargers will be able to increase the power up to 50% of the original horsepower capability. But you will not be able to use this on normal engines because they will not be able to withstand the stress from the additional power.

Turbochargers are used because they will give your engines a gain in power capability without any negative effect on your fuel economy level. The upside is that you can get free horsepower without sacrificing the conservation of energy usage. But the downside is that turbochargers will usually create a lot of problems on your engine. This is why you need to address the problems related to your turbocharger because it can create other engine problems if you ignore it for a long time.

Also, make sure that you never modify the stock turbocharger in your engine especially when you want to increase boost pressures in your vehicle. This is due to the fact that your fuel and timing curve will not be able to adapt to your modification and damages will occur to your engine.

The Causes of Code P0239

Due to the fact that turbochargers spin at high speed, which is around 100,000 to 150,000 RPM, they will be more sensitive to out-of-balance or dirty oil conditions on the bearing. Other causes might include:

● The intake manifold is experiencing a vacuum leak.
● Dirty air cleaner.
● Opened or leaking wastegate.
● An obstruction on the oil feed line causing an insufficiency in oil supply to the shaft bearing.
● Dragging that causes low spin and bearing failure.
● A wobbled bearing that makes turbine blades hit the housing.
● Damaged conditions on the turbine blades that lead to out-of-balance.
● Compressor leak that lets oil deposits on the turbo.
● The shaft is experiencing excessive end play.
● Broken intercooler.
● Disturbed connection from the intake pipe to throttle body.
● Damages on the housing.
● Loose bolts on the exhaust manifold.
● Broken connections on the sensor’s electrical system.
● Shorted connection between the ECM and boost pressure sensor.
● Defects on the ECM or the boost pressure sensor.

The Symptoms of Code P0239

The ECM will store code P0239 when there is a problem with the circuit that prevents proper control of the boost pressure. There might also be other problems related to this code, which should always refer to the specific section of the circuit.

  • The dashboard shows the Check Engine light and the ECM stores the code to its memory.
  • The vehicle might experience a lack of power when you try to accelerate. This is due to the ECM turning off the turbocharger.
  • The boost pressure gauge shows an out-of-range reading level. The level should be between 9 to 14 pounds of boost.
  • You can hear whining sounds from the engine’s turbocharger.
  • Sensor knock code appears indicating a high temperature on the cylinder heads.
  • The engine will experience an overall lack of power, not only when accelerating.
  • Smoke coming out from the exhaust.
  • Your spark plugs get fouled.
  • High engine temperature in normal driving conditions.
  • Hissing noises at the wastegate.

How Your Mechanics Should Diagnose Code P0239

  • The mechanics should analyze freeze frame data to verify the real cause of the problem.
  • The mechanics should clear the code to see if the problem still appears.
  • The mechanics should check the reading levels both on the pressure sensor and the MAP.
  • The mechanics should check for possible blockages on the sensor port.
  • The mechanics should check for damaged pins on turbo boost sensor B.

Common Mistakes when Troubleshooting Code P0239
Following these instructions should prevent misdiagnosis:

  • See if there is any disturbance on the boost pressure sensor.
  • See the integrity of electrical connections and the pressure hoses that are connected to the sensor.

How Serious is Code P0239?

As we said before, turbo boost pressure is the component that will give your engine a gain in power. If there is a malfunction on the turbo boost sensor B, then you will have a problem in giving your engine additional horsepower because the ECM will turn off the turbo boost mechanism.

The Repairs for Code P0239

  • Replace the sensor unit if the reading level is not showing the correct number.
  • Check the damaged electrical connection or hoses and replace them if needed.
  • Repair or replace any damaged connections to the sensor.

Diagnostic Steps and Possible Solutions

Working from top to bottom is usually the most effective way to determine the causes and the correct solution for turbo problems. You will not need complex tools to do this because vacuum gauge and dial indicator are usually enough.

  • Start the engine and confirm that there is no misfiring with the plugs or failures on the knock sensor.
  • Check the condition of clamp tightness on the intercooler and throttle body.
  • Wiggle the turbo housing to see if it is placed tightly.
  • Take the actuating arm away from the wastegate and proceed to operate the valve manually to see if there’s a problem with the boost pressure.
  • With the help of a vacuum gauge, inspect the level of the engine vacuum. Make sure the number is between 16 to 22 inches of vacuum. If the number is out of the range, then the catalytic converter might be in a bad condition.
  • Accelerate the engine spin to around 500 RPM and then let the throttle go. Inspect the vacuum level from the boost pressure. If the level is more than 19 pounds of boost, then the wastegate is your problem. But if the number doesn’t go more than 19, then the problem is with the turbo components.
  • Turn off the engine and let it cool. Open the housing and spin the turbo blades manually to see if they hit the housing parts. You can notice it by the grinding sound it produces. You should also look for bent or damaged individual blades in the turbo.
  • Check the oil lines that feed oil from the engine block to the turbo bearing as well as the return line. Check for any leaks on them.
  • Use the dial indicator on the turbine nose and move the turbo shaft in and out. If the indicator shows that there is over 0.003 of endplay, then you can be sure that there are damages on the turbo bearing.
  • Inspect the voltage level of the boost sensor and harness using volt/ohmmeter. If you can’t detect any voltage, then there might be a shorted circuit in the harness.
  • Check the proper number of reference signals on the ECM that comes from the boost sensor. If the voltage doesn’t rise, then you have a bad boost pressure sensor.

Additional Comments on Repairing Code P0239

Code P0239 appears when there is a malfunction on the boost pressure sensor B and the ECM cannot determine the real cause. But the usual culprit for this problem usually comes from the condition of the boost sensor.

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