Here's what could be wrong and how to troubleshoot:
* Dislodged or Damaged Fuel Level Sender: This is the most probable cause. The sender unit, located in the fuel tank, measures the fuel level and sends a signal to the gauge. During the repair, a mechanic may have accidentally knocked it loose, damaged its wiring, or even broken it. This requires removing the fuel tank (a significant job) to access and inspect/replace the sender.
* Faulty Fuel Gauge Cluster: While less likely, the gauge itself in the instrument cluster could be faulty. This is less probable given the timing of the issue coinciding with the repair. Testing this would require specialized tools to check the signal coming from the sender.
* Wiring Issues: A wire connected to the fuel level sender might have been pinched, broken, or disconnected during the repair. Tracing the wiring from the fuel tank to the gauge cluster is necessary. This could involve some difficult diagnostics and potentially tracing through the vehicle's harness.
What to Do:
1. Return to the Repair Shop: The best first step is to contact the shop that performed the repair. Since the problem arose immediately afterward, it's likely related to their work, and they should diagnose and fix it under warranty. Explain the situation clearly.
2. Professional Diagnosis: If you can't return to the repair shop, you'll need a mechanic to diagnose the problem. They'll use a scan tool to check for diagnostic trouble codes (DTCs) related to the fuel system, and then visually inspect the wiring and potentially access the fuel level sender.
Important Safety Note: Working with the fuel system involves flammable materials. Always disconnect the negative battery terminal before performing any work on the fuel system. If you're not comfortable working on your vehicle's fuel system yourself, you should absolutely seek professional help. This isn't a simple DIY fix.
