The fuel gauge is stuck at Full.
Hi there. By far, the most common cause of this that I have seen is a bad fuel level sensor in the fuel tank. If the sensor fails, it either gets stuck or it shorts and sends the wrong signal consistently. I have also seen issues with the wiring and the rear SAM module that will cause this, but those are not as common. A mechanic would typically test this with a voltage meter and a scan tool. When using a good scan tool they could monitor the signal to the rear SAM. If the signal is making it to the SAM, then the sensor is fine and it may be the SAM or even the gauge. If you planned on having this looked at, consider YourMechanic, as a certified mechanic can inspect the electrical components and repair all the necessary things to make your vehicle run smooth again.
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