Diesel Common Rail Fuel Pressure Sensor (Functions and Symptoms)

Last Updated on December 7, 2019 by themechanic

Diesel common rail fuel pressure sensor also known as fuel rail pressure sensor, commonly used on common rail diesel engines. This is an electronic sensor installed within the fuel rail which makes up the diesel supply pump assembly.

Basic Function and Working Principle

The engine control unit receives fuel pressure information from the fuel rail pressure sensor. Since the engine control unit is the central computer which controls most of a vehicle’s functions, it uses this information to better manage the functionality of the engine itself and the amount of fuel it receives.

The fuel injections must be timed just right. Both the fuel rail pressure sensor and engine control unit work together to ensure this is possible. When the driving conditions change and more pressure is placed on the engine to move the vehicle, then the sensor relays this information to the engine control unit. From there, the unit allows more fuel to be injected for the purposes of going faster and maximizing engine performance.

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5 Common Symptoms

If the fuel rail pressure sensor were to malfunction, then the engine control unit may send the wrong amount of diesel fuel into the engine. It may be too much diesel fuel or too little. Either way, it can have an impact on your engine performance, driving performance, and overall driving expenses too. It is best that you recognize the symptoms of a bad diesel fuel rail pressure sensor before things get worse. Then replace the sensor to fix these issues.

Below are the top 5 symptoms of a bad fuel rail pressure sensor.

1) Trouble Starting Engine

Each time you try to start your engine, it needs a certain amount of fuel to turn on and run. The fuel rail pressure sensor allows the engine control unit to determine the proper amount of fuel needed. But if the sensor is bad, the engine won’t receive the proper amount of fuel it needs. At first, you’ll probably need to crank the engine a couple of times before it finally starts. But the longer this problem continues, it’ll get to the point where the engine won’t start at all.

2) Check Engine Warning Light

Sometimes the Check Engine warning light will illuminate on the dashboard before you experience actual engine issues. This would be a good thing because it’ll give you time to take your vehicle to the mechanic and have them diagnose the problem. However, if you already have engine starting issues and then you see a Check Engine warning light, do not wait another second. Have a mechanic look at your vehicle immediately. It may be a bad fuel rail pressure sensor, or it may be something else.

3) Poor Engine Performance

If your vehicle does not accelerate after you step on the accelerator pedal, then your engine is obviously not getting enough fuel. If you’re experiencing the other symptoms, then it’s logical to think that your fuel rail pressure sensor has gone bad. The engine control unit won’t be able to properly manage your engine’s fuel injections until the sensor is replaced.

4) Engine Stalling

If you’ve still failed to replace your fuel rail pressure sensor, then don’t be surprised if you experience engine stalling. This problem can happen at any time while you’re driving. It can happen when you’re driving on the road or when you’re idle in front of a stop light. Don’t keep driving under these conditions because engine stalling is not safe, and it will keep slowing you down.

5) Poor Fuel Economy

If you care about saving money at the supply pump, then you’ll want to replace your fuel rail pressure sensor after it’s gone bad. Otherwise, it may cause the engine control unit to pump more fuel into the engine than is needed. This increases your vehicle’s fuel consumption, resulting in you having to spend more money on fuel to replenish it.

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