What are the Symptoms of a Bad Fuel Rail Pressure Sensor? | How to Test a Fuel Pressure Sensor

A fuel rail pressure sensor is one of the most important components of the vehicle engine. It assists the vehicle computer to ensure the proper combustion of the air-fuel mixture. When the fuel pressure sensor becomes faulty, you may face different drivability issues. This article explains the bad fuel rail pressure sensor symptoms, causes, and how to test it.

What is a Fuel Pressure Sensor?

The fuel pressure sensor, often known as the fuel rail sensor, is a most important engine management component typically installed in diesel engines and some petrol-injected vehicles. It is an integral part of the fuel system.

The main function of the fuel rail pressure sensor is to continuously measure the fuel pressure within the fuel rail. This information is then relayed to your vehicle’s engine control module (ECM), which utilizes this information to adjust the vehicle’s ignition timing and fuel delivery rate.

The fuel pressure sensor helps to ensure the proper supply of the fuel to the engine.

Automotive sensors can be vulnerable to damage due to continuous exposure to contaminants such as dust, dirt, and high temperatures. The fuel rail sensor is an example of a sensor that may be easily damaged under these conditions.

When the fuel rail pressure sensor goes bad, it doesn’t send the correct information to the PCM or ECM. When the ECM doesn’t receive correct information, it doesn’t precisely adjust the ignition timing and fuel injection rate. In such conditions, you may face different drivability issues, such as poor fuel economy, poor engine performance, or engine stalling.

Symptoms Of a Bad Fuel Rail Pressure Sensor

When the fuel pressure sensor goes bad, it produces one or more of the below-given symptoms:

• Hard Starting
• Poor Fuel Mileage
• Check Engine Light
• Poor Acceleration
• Stalling Engine
• Unburnt Fuel in Exhaust

1) Hard Starting

The fuel rail is responsible for providing the engine cylinder with a consistent supply of fuel. The fuel rail pressure sensor plays a crucial role in ensuring the efficiency of this process.

When the sensor goes bad, it transmits inaccurate data to the PCM, which in turn alters the fuel injection timing and ignition timing which can unintentionally disrupt the fuel supply. As a result, your vehicle may take longer to start.

2) Poor Fuel Mileage

Poor fuel mileage is one of the clear symptoms of a bad fuel pressure sensor. As we discussed above, the main function of this sensor is to measure the fuel pressure inside the fuel rails and send this data to the PCM.

When the sensor is not functioning properly, it may cause an excessive amount of fuel to be delivered to the combustion chamber. This surplus fuel goes unused during the combustion process, leading to other issues as well.

However, there are many other components that may lead to poor fuel efficiency. Therefore, when you face poor fuel economy issues, stop the vehicle and properly inspect all the parts to find the main issue.

3) Check Engine Light

An illuminated check engine light on the vehicle dashboard is one of the clear signs of a faulty fuel rail pressure sensor.

The powertrain control module (PCM) of your vehicle constantly monitors the performance of the pressure sensor. When the PCM detects an issue with the signal coming from the fuel rail sensor, it triggers the check engine light to alert you to a potential engine-related problem.

However, it’s important to note that there are numerous other reasons why the check engine light might turn on, aside from a faulty fuel rail sensor.

Read More: How To Reset Check Engine Light

4) Poor Acceleration

If you experience a lack of acceleration when pressing the gas pedal, it could indicate an issue with the fuel rail sensor.

As discussed above, an issue with the fuel pressure sensor may disrupt the optimal air-fuel ratio, leading to a clear decrease in your vehicle’s power while driving.

5) Stalling Engine

An irregular fuel supply to the combustion chamber may lead to unusual stalling, and often, your engine may not restart. If this occurs regularly, it means that there may be an issue with the fuel rail pressure sensor, which is preventing it from sending accurate information to the PCM.

If your vehicle’s PCM cannot make the necessary adjustments, the vehicle is at a heightened risk of developing problems that could have been avoided otherwise.

6) Unburnt Fuel in Exhaust

When a fuel rail sensor is faulty, it may cause an excessive amount of fuel to be transferred to the engine cylinder. As a result, some fuel remains unburned at the end of each cycle, ultimately ending up in your vehicle’s exhaust system.

This unburned fuel enters the catalytic converter, impairing its ability to reduce emissions effectively. Furthermore, poor combustion of the air-fuel mixture may take place, which can generate harmful gases that the catalytic converter may not be able to neutralize entirely.

Causes of Bad Fuel Pressure Sensor

Your fuel rail pressure sensor may go bad due to one or more of the following causes:

• Faulty Fuel Lines
• Faulty Fuel Pump
• Manufacturing Defect
• Corrosion or Wear
• Clogged Fuel Filter
• Excessive Heat or Temperature Fluctuations
• Damaged Fuel Tank

1) Faulty Fuel Lines

A damaged fuel line is one of the major causes of a faulty fuel rail pressure sensor. Various problems can contribute to a problematic environment within the fuel system.

2) Faulty Fuel Pump

A faulty fuel pump may produce different complications for the fuel rail sensor as well. Although this sensor is designed to be durable, it is meant to function under normal operating conditions.

A defective component within the fuel system may impact the entire system’s performance.

3) Manufacturing Defect

It is important to consider that a part may be inherently faulty. These components are produced in large quantities, and it would be unrealistic to expect that every single part coming off the assembly line is without defects.

4) Corrosion or Wear

Over time, corrosion or general wear and tear may badly affect the fuel pressure sensor, causing it to malfunction or fail.

5) Clogged Fuel Filter

A clogged fuel filter may impede fuel flow or introduce dirt into the fuel lines. This can lead to a restricted fuel supply line, which may further negatively affect the fuel pressure regulator.

6) Excessive Heat or Temperature Fluctuations

Your vehicle’s sensors, including the fuel rail sensor, are sensitive to intense heat or rapid temperature changes, causing them to wear out or fail early.

7) Damaged Fuel Tank

A leaked or damaged fuel tank may also result in a malfunctioning fuel rail pressure sensor. A leaking tank, the presence of solid debris, or excessive air can all cause issues that propagate throughout the system.

Fuel Pressure Sensor Location

The location of the fuel rail pressure sensor varies according to the vehicle’s make and model. The fuel rail pressure sensor is usually located on the fuel rail, which is typically situated close to or beneath the intake manifold.

In a few vehicles, it may be located on the fuel line instead, although this placement is less common.

Fuel Pressure Sensor Replacement Cost

The replacement cost of the fuel pressure sensor varies according to the vehicle model, labor cost, and the type of sensor brand.

The average replacement cost of the fuel rail pressure sensor is from $90 to $320. In this cost, the labor costs from $40 to $140, while the sensor costs from $50 to $180.

Fuel Rail Pressure Sensor Testing

FAQ Section

What is the function of the fuel pressure sensor?

The main function of the fuel pressure sensor is to continuously measure the fuel pressure within the fuel rail and send this data to the vehicle’s powertrain control module (PCM), which utilizes this information to adjust the vehicle’s ignition timing and fuel delivery rate.

What happens if the fuel rail sensor goes bad?

When the fuel rail sensor goes bad, it produces different symptoms, such as poor engine performance, check engine light illumination, poor fuel economy, poor acceleration, engine stalling, or hard engine starting.

How can I tell if a fuel pressure sensor is bad?

Indications of a faulty fuel pressure sensor can include a check engine light on the dashboard. To further assess the issue, you can use a diagnostic scanner or a multimeter to check the sensor’s values.

Can I clean my fuel rail pressure sensor?

A clogged or dirty fuel rail pressure sensor can’t work efficiently. Although it’s rare for a sensor to cease functioning solely due to dirt accumulation, it’s better not to take chances. For thorough cleaning, it is recommended to consult a qualified mechanic.

How do you test a fuel rail pressure sensor?

To test the fuel rail pressure sensor, connect a diagnostic scanner and compare the reported values to those found in the repair manual. Alternatively, you can use a multimeter to examine the sensor, but be sure to obtain the correct measurement values for the specific sensor.

Can I drive with a bad fuel pressure sensor?

Yes, you can drive but it is not recommended to drive with a faulty fuel pressure sensor. Driving with a bad pressure sensor may produce different drivability issues such as poor fuel economy, engine stalling, poor acceleration, or misfiring.

What are the signs of a bad fuel pressure sensor?

• Unburnt fuel in the exhaust
• Hard starting
• Poor fuel mileage
• Poor acceleration
• Check engine light
• Stalling engine

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