* Faulty Fuel Sender Unit: This is the most common culprit. Located in the fuel tank, the sender unit measures the fuel level and sends a signal to the gauge. A broken or corroded sender unit, or a faulty float inside it, will provide inaccurate readings or no reading at all.
* Wiring Problems: Worn, corroded, or broken wires between the fuel sender unit and the instrument cluster can interrupt the signal. This is particularly likely in older cars where the wiring harness may be subject to wear and tear. Look for broken wires, loose connections, and corrosion near the fuel tank and at the instrument cluster.
* Instrument Cluster Issue: The fuel gauge itself within the instrument cluster could be faulty. This is less common than a sender unit problem, but it's possible the gauge's internal components have failed.
* Grounding Issues: A poor ground connection anywhere in the circuit can cause erratic readings or a complete failure of the gauge. Check the ground connections at the fuel tank and the instrument cluster.
* Fuel Pump Relay or Fuse: In some cases, a problem with the fuel pump relay or a blown fuse can indirectly affect the fuel gauge readings. While unlikely to cause a total failure, it could lead to inaccurate readings.
* ECM (Engine Control Module) Problems: Although less frequent, a malfunctioning Engine Control Module (ECM) can potentially interfere with the fuel gauge signal processing.
Troubleshooting Steps:
1. Check the Fuel Pump Relay and Fuse: Start by examining the fuel pump relay and fuse to ensure they are functioning correctly. Replace if necessary.
2. Visual Inspection: Carefully inspect the wiring harness from the fuel tank to the instrument cluster for any visible damage, corrosion, or loose connections.
3. Fuel Sender Unit Test: This often requires dropping the fuel tank (a significant undertaking), and many mechanics test this first. A multimeter can be used to measure the resistance of the sender unit at different fuel levels. (There are charts available online that give the resistance expected at different fuel levels).
4. Instrument Cluster Test: If the sender unit tests OK, the instrument cluster itself needs further investigation which may involve specialized testing equipment.
Important Note: Working with fuel systems involves potential fire hazards. Always disconnect the negative battery terminal before starting any work. If you are not comfortable working on car electrical systems, it's best to take your Intrigue to a qualified mechanic for diagnosis and repair. They have the tools and expertise to properly diagnose and fix the issue safely and efficiently.
