Replacing The Fuel Composition Sensor In A 2004 Yukon

If you're experiencing problems with your 2004 Yukon, you may need to replace the fuel composition sensor. This sensor is responsible for measuring the ethanol content in the fuel used by the vehicle. A faulty sensor can lead to a range of issues, including decreased fuel efficiency, rough idling or stalling, and reduced engine performance. Replacing the sensor typically involves removing a few bolts, disconnecting fuel lines, and dealing with electrical connectors. It is recommended to consult a qualified mechanic or refer to a repair manual for specific instructions for your vehicle.

Location of the fuel composition sensor

The fuel composition sensor on a 2004 Yukon is located on the rear frame crossmember. More specifically, it is located between the driver's side frame rail and the transfer case drive shaft, ahead of the fuel tank.

To replace the sensor, you will need to remove a few bolts, an electrical connector, and some quick-disconnect fuel lines. Be sure to remove the fuel lines carefully, as there may still be pressure in the fuel system. It is recommended to relieve the pressure in the fuel system before removing the lines to avoid fuel spray. This can be done by using a fuel pressure gauge to drain the pressure or by removing the fuel pump relay while the engine is running.

How to remove the sensor

To remove the fuel composition sensor on a 2004 Yukon, you will first need to locate it. The sensor is situated on the rear frame crossmember, between the driver's side frame rail and the transfer case drive shaft, ahead of the fuel tank.

Once you have located the sensor, you can begin the removal process. The process is relatively straightforward and involves removing a few bolts, an electrical connector, and some quick-disconnect fuel lines. However, it is important to be cautious when removing the fuel lines, as there may still be pressure in the fuel system, which could cause fuel to spray out.

To reduce the risk of fuel spray, you can either use a fuel pressure gauge to drain the pressure or remove the fuel pump relay while the engine is running and wait for it to die. Even if you release the pressure, there may still be some fuel leakage when you remove the lines, so caution is advised.

After disconnecting the fuel lines, simply unplug the electrical connector and unscrew any bolts holding the sensor in place. Be sure to keep the bolts in a safe place so that you can reuse them when installing the new sensor.

How to install the new sensor

To install the new fuel composition sensor, follow these steps:

• Locate the sensor on the rear frame crossmember, between the driver-side frame rail and the transfer case drive shaft, ahead of the fuel tank.
• Remove the old sensor by carefully disconnecting the fuel lines, electrical connector, and bolts. Be cautious, as there may still be pressure in the fuel system.
• Install the new sensor by securing it with the bolts, connecting the electrical connector, and carefully attaching the fuel lines. Ensure all connections are secure to avoid any leaks.
• Start the engine and check for any leaks or issues.

It is important to follow the GMC replacement procedure and take appropriate safety precautions when working with fuel systems. If you are unsure or uncomfortable with any part of the process, it is recommended to consult a certified mechanic.

Common issues and costs

The GMC Yukon is a large vehicle with a powerful engine, and like any car, it has its common issues. One of the more prevalent problems is erratic fuel gauge operation, which can be caused by a faulty fuel level sensor in the fuel tank. This issue has been reported by many GMC Yukon owners, and the recommended solution is to replace the sensor or the entire fuel pump module, especially for high-mileage vehicles.

Another common problem with the GMC Yukon is related to the fuel tank pressure sensor. This sensor helps control fuel vapour emissions and alerts the car's computer to any drop in pressure. While the sensor itself doesn't commonly malfunction, it can indicate issues with other parts of the EVAP system, such as the gas cap. If the sensor is faulty, it will need to be replaced, which can cost between $306 and $362 for parts and labour.

The fuel composition sensor is also an important component in the GMC Yukon's engine. This sensor measures the ethanol content in the fuel, and if it malfunctions, it can lead to an improper fuel mixture and affect engine performance. The cost of replacing this sensor typically ranges from $150 to $300, but additional costs may be incurred for wiring repairs or ECM reprogramming.

Some other common issues with the GMC Yukon include:

• Transmission Pressure Control Solenoid Failure
• Nissan Crankshaft and Camshaft Sensor Recall
• Harsh or Delayed Shifting of Automatic Transmission
• Reduced Power and Check Engine Light
• Stalling or Low Engine Idle Speed due to Dirty Throttle Body
• ABS Light due to Poor Electrical Ground under the Battery Tray

Tools needed

To replace the fuel composition sensor on a 2004 Yukon, you will need the following tools:

• A fuel pressure gauge to relieve the pressure in the fuel system. Alternatively, you can remove the fuel pump relay while the engine is running and wait for it to die. This relay is in the underhood fuse block and is labelled 'fuel pump' or 'FP'.
• Tools to carefully remove the fuel lines. Be aware that there will still be some pressure in the lines, and fuel may spray out.
• A tool to remove bolts, as there are a few bolts attaching the sensor to the vehicle.
• A tool to remove the electrical connector.

Frequently asked questions