P1456 indicates that the engine control module has detected an abnormal signal from the fuel tank temperature sensor circuit. The sensor provides fuel temperature data used for evaporative emissions calculations and fuel system management. A malfunction can be caused by the sensor itself, its wiring, or a rare control module fault.
The sensor element may become open or shorted, sending an out-of-range voltage to the control module.
Corrosion, chafing, or a loose connector can create high resistance or an open/short condition.
A break or short to ground/power in the signal line prevents the module from reading a valid temperature.
Internal driver or ADC failure can misinterpret a good sensor signal, but this is only considered after all other causes are eliminated.
The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:
No. The control module is the least likely cause; replacement is only justified after the sensor, wiring, and circuit have been verified good.
A loose cap typically sets evaporative system codes such as P0442 or P0455, not a fuel tank temperature sensor circuit code.
It monitors the temperature of fuel in the tank so the control module can calculate vapor pressure and manage evaporative emissions purging.
In most cases drivability is unaffected; the code primarily impacts emissions readiness and may cause a slight fuel gauge inaccuracy.