The fuel management system in your car consists of multiple sensors and modules that measure multiple data points to help your car run smoothly. It’s important that all of these sensors and modules function the way they’re supposed to; if even one of them fails it can have pretty noticeable effects on your driving experience.
The fuel pressure sensor is one of these sensors, and if it fails then it can significantly decrease your car’s ability to supply its engine with the right amount of fuel. This can lead to symptoms like weak acceleration, difficulty starting the car, stalling, and poor fuel economy.
Today, we’ll be going over in detail what exactly the fuel pressure sensor in your car does and what the symptoms of a failing sensor are. We’ll also walk you through how to change your car’s fuel pressure sensor yourself, and answer a few other questions you might have about this sensor.
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- What Is a Fuel Pressure Sensor, and What Does It Do?
- What Are the Symptoms of a Bad Fuel Pressure Sensor?
- Can I Drive With a Bad Fuel Pressure Sensor?
- How to Replace Your Car's Fuel Pressure Sensor
What Is a Fuel Pressure Sensor, and What Does It Do?
The fuel pressure sensor is also referred to as the fuel rail pressure sensor, and shouldn’t be confused with the fuel tank pressure sensor which is located in a completely different part of the car. As the full name of this sensor implies, the fuel pressure sensor is located in the fuel rail and monitors the fuel pressure within the rail.
Along with the data received from airflow sensors, throttle position sensors, and the various other sensors within the fuel management system, the ECU (engine control unit) uses the data it gets from the fuel pressure sensor to make adjustments to the amount of fuel being sent to the cylinders and the ignition timing.
It’s important that your ECU receives the right data because it helps your engine run as smoothly and efficiently as possible while also producing sufficient power. If the fuel pressure sensor fails, it can throw off the accuracy of the entire fuel management system.
What Are the Symptoms of a Bad Fuel Pressure Sensor?
The symptoms of a bad fuel pressure sensor are more or less the same as the symptoms of other fuel system-related issues. If you notice any of these symptoms occurring, there’s a chance it might be another component of your fuel management system that is causing the issues.
Regardless, if you encounter the following symptoms, it means that something is definitely wrong with your car’s fuel management system, which should at least let you narrow down the potential sources of the problem.
Here are the symptoms of a bad fuel pressure sensor that you should look out for:
1. Trouble Starting Your Car
As we’ve mentioned, the point of the fuel pressure sensor is to measure the pressure of the fuel in the fuel rail, which gives the ECU an approximate measurement of how much fuel is in the fuel rail to begin with. This helps the ECU send the correct amount of fuel to the engine, depending on the situation.
If your faulty sensor is causing your engine to run lean, the ECU might fail to realize that there is not enough fuel entering the fuel fail and be unable to make the correct adjustments. In such cases, you’ll notice that you have to crank your engine a lot more before it actually starts.
If your engine continues to run lean as a result of your bad fuel pressure sensor, you could run the risk of stalling while idling or in the middle of driving. This, of course, can happen if the amount of fuel making it to the engine isn’t enough to sustain the load of the engine.
If your engine stalls while you’re idling, that’s one thing, but if it stalls when you’re on the move then it can present a pretty serious safety risk. If you’re at the point where your engine is actually stalling because of fuel issues, you need to take your car in for repairs as soon as you can.
3. Poor Acceleration
Again, this is another problem that can result from your engine running lean because of a bad fuel sensor. If your engine isn’t getting enough fuel when it needs it, it will be unable to produce any more power when you ask it to.
4. Poor Fuel Economy
On the other hand, if a bad fuel pressure sensor is causing your engine to run rich, you’ll most likely notice it when you’re all of a sudden spending way more money than normal on your gas. That’s why it’s important to have a good understanding of your car’s normal mileage, so you’re not caught too badly off guard if this should happen.
Other signs that your car is running rich include smelling gas when driving, especially when your engine is at idle. Letting your engine run rich for too long can end up damaging components of your exhaust system like your catalytic converter, so it’s always a good idea to fix this issue as soon as possible if you encounter it.
5. Check Engine Light Is On
The check engine light will always be the most obvious sign that something is wrong with your car. The check engine light will activate whenever the ECU logs an error code. Obviously, the check engine light doesn’t necessarily mean there’s a problem with your fuel management system specifically, but a fuel system issue can definitely be the cause of a check engine light.
If you have an OBD2 scanner tool, you can also try connecting to your car’s computer and seeing what error codes it has logged. You’ll want to look for the following codes which are the most common codes related to the fuel pressure sensor:
Can I Drive With a Bad Fuel Pressure Sensor?
You can, in theory, as long as the issue isn’t too bad. If your fuel pressure sensor has just started to fail, you would probably still be able to drive your car to a repair shop without any problems. However, the longer you go with a failing fuel pressure sensor, the worse your problems are going to get.
Eventually, you’ll get to the point where starting your car and keeping it running becomes a Sisyphean task. You’ll have to worry about your car stalling on your every time you drive it, and if it does happen to stall at an inconvenient time, it could be a huge safety risk, not just for you but the other drivers on the road with you.
Put simply, you can drive with a bad fuel pressure sensor for a little bit, but doing so for any longer than you absolutely have to is a pretty terrible idea.
How to Replace Your Car’s Fuel Pressure Sensor
First off, we should mention that unless you have the proper tools and experience to complete a repair like this, you should probably just let a professional take care of it. Replacing a bad fuel pressure sensor isn’t the hardest repair to make, but if you don’t know what you’re doing then you might end up making it a lot harder than it needs to be.
Assuming you do have the necessary skills and equipment to handle a repair like this, however, here’s what you need to do:
- Disconnect the negative cable from your battery. Since you’ll be working on your car’s electronics, you should do this to avoid accidentally electrocuting yourself.
- Remove the plastic cover from your engine, if there is one. Depending on the layout of your engine, you may have to remove your air intake to gain access to the fuel rail and sensor.
- When you’ve found your fuel rail, locate the test port on it. Put a drip pan under the test port, and open the test port’s valve with a small screwdriver to depressurize the fuel rail.
- Disconnect the electrical harness and the mounting hardware from the fuel pressure sensor, and remove it from the fuel rail.
- Clean the fuel rail and the sensor’s electrical harness before installing the new sensor.
- Install the new sensor onto the fuel rail, making sure to fully tighten the mounting hardware.
- Reconnect the electrical harness to the new sensor. If you had to remove the air intake to access the fuel rail, you can reattach it now.
- Replace the engine cover, and reconnect the negative cable to your battery. If you did everything correctly, you should now be good to go!