The fuel tank pressure (FTP) sensor is a vital evaporative emission control system (EVAP). The EVAP system traps unburnt fuel vapor from the gas tank and transports it back to the fuel system. This offers a high fuel economy, minimizes environmental pollution, and prevents premature engine damage. What is a fuel tank pressure sensor, anyway?
The FTP sensor is normally placed on top or inside the gas tank. Its primary function is to detect the pressure in the fuel system and enhance fuel economy. If it fails, it’ll decrease the amount of gas in the combustion chamber. This can cause engine stalling, weak acceleration, bad gas mileage, and hard starting.
In this article, we’ll discuss what causes a fuel tank pressure sensor to go bad. And how to test a fuel tank pressure sensor. We’ll also outline the symptoms of a bad fuel tank pressure sensor and answer related questions.
What Does The Fuel Tank Pressure Sensor Do?
As the name suggests, the FTP sensor reads the gas pressure in the fuel system. This helps you to determine if there is a leak in the fuel system, especially the one related to evaporation. Remember, the FTP sensor is an evaporative emission control system (EVAP) component.
If a leak exists on the gas cap or vapor is escaping anywhere in the system, the FTP sensor will notify you.
The FTP sensor works in harmony with the powertrain control module. The FTP sensor relates all the collected data to the car computer. For this reason, if the fuel tank pressure sensor determines a problem or leaks in the fuel system, the engine control module will trigger the engine warning light.
The illumination of the engine warning light is to notify the driver of any imminent issues in the system. The engine check light doesn’t necessarily mean any issue with the fuel tank pressure sensor. Therefore, once the engine warning light illuminates the dashboard, diagnose the vehicle with an OBDII scanner.
An OBDII diagnostics tool will determine why the car computer triggers a light and pull out logged diagnostics trouble codes. The error code will relate to the culprit, making it easier for a mechanic to track and fix it.
If you are a DIYer, you can get a diagnostic scanner from a local auto shop or Amazon for around $200. This tool will not fix the problem for you; however, it’ll narrow down to the cause of the problem and ways to rectify it.
Symptoms Of A Bad Fuel Tank Pressure Sensor
Calm your nerves when you’re wondering, ‘what happens when a fuel pressure sensor goes bad?’ Yes, there is good and bad news to expect. The awesome news is there are chances your car will run pretty fine. It may not affect your car performance in any way.
The sad news is that the vehicle will fail the emission test when the FTP sensor malfunctions. Of course, the engine warning light will appear on the dashboard.
And if you leave the light, thinking it appeared because of a bad FTP sensor, you won’t know when the car computer logs another issue, leading to catastrophic engine damage.
Here are other notable symptoms of bad EVAP fuel tank pressure sensors that show when the FTP sensor is bad.
Engine warning light
As we explained above, the engine warning light will illuminate when the FTP sensor malfunctions. The car computer will log diagnostics trouble code P0452. Of course, there can be many causes. It could be a broken seal on the gas cap or a leak in the fuel system.
Bad gas mileage
When any fuel system sensor sends false information regarding fuel usage to the car computer, it’ll cause poor fuel economy. If the engine control module doesn’t know how much fuel the vehicle uses and how much gas to maintain an appropriate speed, the car will consume much fuel. This will lead to bad engine performance. You may have poor engine power output, poor acceleration, and lower miles per gallon.
If you notice a frequent engine stalling or hesitation, it could mean the FTP sensor is bad. Since the car computer also uses the signal from the FTP sensor in calculating the fuel/air mixture ratio for the combustion process, a false reading can affect the combustion cycle. A compromised combustion process will lead to improper fuel burning, which will cause engine hesitation and stalling.
Hard engine starting
As much as a lousy FTP sensor can compromise the combustion process, it can make the engine difficult to start. If this sensor signals false reading to the powertrain control module, it can lead to a lean air-fuel mixture. This means a higher volume of air and a smaller volume of fuel. The engine may find it difficult to start with an inappropriate fuel mixture.
How Do I Test A Fuel Tank Pressure Switch?
Checking the FTP sensor is pretty simple. It is a three-wired component that is quite easy to test. The three wires are a ground wire, a voltage wire that goes to the engine control module, and another wire that returns volts to the ECM.
So, if you suspect a bad FTP sensor, check these wires to know if the FTP switch is bad or if the problem is from somewhere else.
Unfortunately, you may have to drop the gas tank to access the FTP sensor because it is mounted on top or inside the gas tank. For this reason, it is typically inaccessible for an average motorist, which explains why you need to consult your mechanic to check and replace the sensor.
However, here are a few ways to follow if you decide to check the FTP sensor yourself.
- Locate the sensor
- Unplug the wiring harness
- Connect your multimeter or voltmeter
- Compare the reading on the voltmeter and compare the specified signal on your manual. Ensure the readings are the same.
- Check the wiring harness and replace corroded or burnt wires.
For a visual presentation on how to test the FTP sensor, watch this YouTube video.
How Do You Fix A Gas Tank Sensor?
If the test proves you have a defective FTP sensor, you may ask, can you drive with a bad tank pressure sensor?
As we explained earlier, a bad FTP sensor cannot affect the overall engine performance. It can also project several drivability issues and trigger engine check lights on the dashboard. For this reason, do not drive with a defective gas tank sensor.
So, what should you do, then?
Fix it before hitting the road. Unfortunately, the only recommendation to fix the FTP sensor is to replace it. The sensor is pretty inexpensive, but the replacement cost can be high depending on your fuel tank design.
Q: Can a bad fuel pressure sensor cause no start?
If you have a lousy FTP sensor, it can cause the fuel injectors to send an obscene amount of gas to the combustion chamber. This can lead to hard starting.
At first, it will only take a few attempts before turning on the vehicle. But as the case worsens, it’ll take several attempts before starting the vehicle. If you keep ignoring it, it may get to a state where the engine will start and shut off. In rare situations, it may cause the engine not to start at all.
Q: Can a bad fuel pressure sensor cause a misfire?
Like fuel pressure regulators, the common sign of a bad FTP sensor is weak acceleration and engine misfire. You’ll notice a sudden loss of engine power output when driving. The vehicle may stumble, hesitate, or even bog when taking an early morning ride or on a sunny afternoon.
The acceleration may become pretty fine in no time and suddenly fail again. This can be dangerous. Therefore, do not drive with a bad FTP sensor if it gives sudden changes in the accelerations.
Q: How long does a fuel tank pressure sensor last?
Automakers design FTP sensors to last the vehicle’s lifespan like most car sensors and switches. However, the sensor can break when working on the fuel tank because of its location. A mechanic may mistakenly break it when working on the gas tank. It can also wear on the terminals and damage.
Q: How much is a fuel tank pressure sensor?
The average replacement cost for an FTP sensor is $250 to $325. The parts should be around $50 to $75, while the labor charge is around $200 to $250.
This is a general replacement estimation. It doesn’t deal with any specific vehicle make or model. Other factors, like taxes, location, and related repairs, may increase or reduce the replacement cost.
Q: Can you clean a fuel pressure sensor?
Of course, you can clean a fuel pressure sensor, but there are huge chances that it won’t make any difference. Because of the location of the sensor, dirt can clog the terminals and prevent them from sending accurate signals to the car computer. If this is the case, cleaning will revive the sensor. However, in most cases, the only option is to replace the sensor.
Q: Can you bypass a fuel tank pressure sensor?
Fuel tank pressure sensor bypass is a ‘hit or miss’ repair. You can plug or bypass the pressure sensor. But once you bypass it, the check engine light will illuminate on the dashboard.
The FTP sensor is one of those important components many motorists do not know in a car. However, the signal from this sensor offers a good fuel economy, saves you some cash, and enhances optimal engine performance.
Unfortunately, symptoms of a bad fuel tank pressure sensor can be mistaken for other system malfunctions. Therefore, if you notice any of the outlined signs above, ensure you diagnose the vehicle with a scan tool. This will help you fix the culprit without doing guesswork.