While a turbocharger or supercharger can significantly enhance your vehicle’s overall power output, there are other parts of your vehicle that can generate more power.
However, these powerful engine components require the vehicle to monitor the components to ensure everything is going according to plan.
This is where the boost pressure sensor comes in. But how can you tell if the boost pressure sensor is faulty? And what does a boost pressure sensor actually do?
Boost pressure sensors are used in turbocharged engines to provide air pressure information and air and fuel ratio to affect engine performance. A boost pressure sensors is a highly technical piece of technology, and certainly an impressive addition to the world of engine technology.
Essentially, boost pressure sensors control the boost level produced in the intake manifold of a turbocharged engine or supercharged engine. Boost pressure sensors will influence the air pressure utilized by the pneumatic and mechanical wastegate actuator.
We’ll break it all down here then, but first let’s take a look at the price and where a busted boost pressure sensor will hit you in the pocket with a replacement. Let’s start with the bad boost pressure sensor symptoms and what to look out for.
What is a Boost Pressure Sensor?
A Turbo Boost Pressure Sensor measures the amount of boost pressure in the intake manifold. The engine control module uses the boost pressure sensor information to determine how much fuel to inject, how to time the ignition properly and how to operate the turbocharger’s wastegate.
The boost pressure sensor tells the ECM how much boost the turbocharger or supercharger is producing, because the computer wants a specific amount of boost, but it has to measure the amount of boost it requests from the turbocharger or supercharger.
The boost pressure sensor tells the ECM what is happening with the fuel to air ratio, to have the engine running on optimal performance. It also acts as a safeguard to protect the engine, if the supercharger or turbocharger is not working correctly.
Boost Pressure Sensor Location
The boost pressure sensor for your vehicle is typically located on the boost pipes, between the intake manifold and the turbo. On some other vehicles, it can also be located on the intake manifold itself.
While this area makes it easy to measure the boost pressure that the supercharger or turbo creates, it is not in the way of anything.
In reality it’s a pretty simple location near the top of the engine, but you may have to remove a couple of things to gain access to it. However, in the grand scheme of things it is one of the easier components to locate and access when it comes to finding the boost pressure sensor.
How Does A Boost Pressure senssor Work?
The boost pressure sensor measures the absolute pressure upstream of the throttle valve. The engine control unit (ECU) uses its input to calculate a correction value for boost pressure.
At the ECU, proper air-fuel ratio is calculated if the ECU can determine the amount of boost and air density in the car’s intake manifold, allowing the ECU to determine how much fuel is needed in the combustion chamber for the best air-fuel mix.
Proper air-fuel mixture is paramount to engines because proper air-fuel mixture leads to better and more efficient power. Proper air-fuel mixture not only makes engines powerful but efficient, getting the most out of every drop of fuel.
When the manifold pressure is low (high vacuum) sensor voltage output is 0.25 – 1.8 V at the ECM. When the intake manifold pressure is high with turbo boost, sensor voltage output is 2.0 – 4.7 volts.
The pressure range is 10kPa to 350kPa. The sensor receives a 5-volt reference to the ECM as well as the sensor’s ground. The ECM determines the volume of air entering the engine using boost pressure in conjunction with intake air temperature.
Symptoms Of A Bad Boost Pressure Sensor
The most common signs of a bad or failing boost pressure sensor is reduced or increased engine performance and a check engine light on your dashboard.
If your vehicle has a boost pressure gauge, you will also be able to see if the boost pressure increased or decreased. If you are interested in a closer look at these signs, here is a more detailed list of the signs of a bad or failing boost pressure sensor to look for.
#1. Check Engine Light.
If your boost pressure sensor is bad, you are going to have a check engine light. More specifically, you will have a code P0236. If you have this engine code, chances are that your sensor to measure boost pressure is bad, however it could be something else also.
You will still need to rule out an underlying electrical issue and verify that there isn’t anything wrong with your turbo or supercharger. If there is an underlying issue, then your boost pressure sensor is do what it is supposed to be doing – and that is alerting you that there is an underlying issue.
#2. Reduced or Increased Engine Performance.
Your boost pressure sensor sends a signal to your ECM explaining what the real output of your turbo or supercharger is, so if the sensor isn’t sending accurate numbers, the ECM is adjusting to the inaccurate numbers causing either a lesser engine performance or a greater.
A bad boost pressure sensor will cause a more noticeable drop in performance in a turbocharged engine compared to a supercharged engine, though a drop in engine performance can happen in either.
That is because, in either case, the ECM simply has no idea how well the supercharger performs on a supercharged engine to optimize performance, the ECM only knows how well the engine itself is performing.
However, in a turbocharged engine the ECM may delete or fail to use the turbocharger altogether, which will cause a very large drop in performance.
In rare cases, the ECM can increase the turbo pressure, which might improve performance in some cases. That can be detrimental to your engine though, so you do want to take care of this problem as soon as possible.
#3. Decrease or Increase in Boost Pressure.
In the previous symptoms section, we discussed how a bad boost pressure sensor can increase or decrease engine performance due to an increased or decreased turbo pressure.
Some models do have a turbo pressure gauge which will show you turbo pressure real-time. If you observe if the turbo pressure is lower or higher than normal under increased loads, it can absolutely be caused by a bad boost pressure sensor.
Boost Pressure Sensor Replacement Cost
The cost for an average boost pressure sensor is approximately $175-$200; however, this price may change depending on your car and driving it to a repair shop. If you are wanting to replace this sensor yourself, you can since most of the cost goes to the part and not labor.
The average cost for a boost pressure sensor is more than $125; however, you are not saving a lot of money and changing it out is not difficult if you wanted to do that yourself. The most you will have to do is disconnect the battery, then unplug the electrical connector and remove the bolt holding the sensor on.
From there, you would install the new one by bolting it back on, plugging it back in, and tuning the battery back on. If the boost pressure sensor is the issue, you should be good to go now.
Can You Drive With a Faulty Boost Pressure Sensor?
Never operate a vehicle with a bad boost pressure sensor. Without a boost pressure sensor, it’s commonplace for the ECM to send far too much power to the turbocharger. This can lead to catastrophic damage to your engine.
By not replacing something that costs most likely less than $200 for the part, you could easily cause several thousand dollars of damage, and you could even total your engine. This occurs because too much boost ultimately causes the engine to overheat, which damages components in the engine.
If you do not have the money to replace your boost pressure sensor, it’s much better to keep the vehicle in the garage rather than operating it until you get it repaired. It may be very inconvenient, but do not risk other huge bills.
If you suspect your boost pressure sensor is bad or working improperly, get the sensor checked by a certified auto mechanic right away. Given how the engine operates, you should expect your car will have issues with the boost pressure sensor, and it will only hurt your engine further.
Always start diagnosing issues with the engine by reading the fault code memory from the ECM with an OBD scanner. This will provide very useful information that will save you money.