Depending on how the gauge works, disconnecting the sensor, or connecting it to ground, may allow you to take a look at the operation of the gauge.
Dabere n'otú nlele ahụ si arụ ọrụ, ịkwụsị ihe mmetụta ahụ, ma ọ bụ ijikọ ya na ala, nwere ike ịhapụ gị ịnwale ọrụ nke nlele ahụ.