Aircraft modified with G3X Touch AML STC SA01899WI, MDL Revision 7 or earlier, with interface to resistive fuel senders with less than or equal to 100 ohms range are affected.
FAA STC SA01899WI MDL Revision 7
Mandatory: This STC Service Bulletin must be incorporated for affected installations and is warranty reimbursable.
When operating at low fuel, the G3X Touch fuel quantity gauges may indicate up to a four (4) gallon error if connected to a resistive fuel sender with a range of less than or equal to 100 ohms. The potential for this error is greater when the GEA 24 is subject to significantly hotter or colder temperatures than the temperature at which the fuel gauges were calibrated during installation.
This issue is described in Garmin Service Alert 20137.