But sometimes the fuel level sensor contacts are too far gone to be fixed by a cleaning. If the fuel additive did not fix the problem, a failing or failed fuel sending unit is the most likely cause.

General Motors has agreed to pay to repair the fuel gauges in several GM SUVs, following a defect investigation by the National Highway Traffic Safety Administration.

The fix: GM will notify owners, and dealers will replace the rear tank fuel pump or update the fuel-level sensor software.

Documents posted Thursday by the U.S. government say that the low-fuel-level sensor in the front tank can stick, causing the rear tank to over-fill the front tank.

Within the fuel level sensor are small metal parts which send the readings to the driver’s dashboard and cause the light to flash.