Faulty fuel tank temperature sensor (internal failure or drift); Damaged or corroded wiring harness at the sensor connector or along the body; Open or short circuit in the sensor signal or ground circuit; Loose or contaminated electrical connector pins at the sensor; Failed PCM driver or internal pull-up resistor (less common); Fuel contamination or extreme temperatures causing sensor misreading (indirect cause)

DTC codes / Mazda codes / P1456

P1456 · MazdaFuel Tank Temperature Sensor Circuit

Q: What does code P1456 mean?

Fuel Tank Temperature Sensor Circuit. P1456 on a Mazda means the powertrain control module (PCM) has detected an abnormal signal from the fuel tank temperature sensor circuit, which is used to monitor fuel temperature for evaporative emission control. The PCM compares the sensor's voltage against expected values and flags the code when the reading falls outside the normal range for a calibrated period.

P1456 on a Mazda means the powertrain control module (PCM) has detected an abnormal signal from the fuel tank temperature sensor circuit, which is used to monitor fuel temperature for evaporative emission control. The PCM compares the sensor's voltage against expected values and flags the code when the reading falls outside the normal range for a calibrated period.

SystemPowertrain

Code typeMazda specific

SeverityLow

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
A slight fuel smell or evaporative emission system odor in some cases
Rough idle or hesitation if the faulty circuit affects fuel trim calculations
Increased fuel consumption due to incorrect temperature compensation
Failed emissions inspection because the evaporative system monitor is incomplete
In rare cases, a no-start condition if the sensor shorts and disrupts shared reference voltage

Common causes, most likely first

Faulty fuel tank temperature sensor (internal failure or drift)
Damaged or corroded wiring harness at the sensor connector or along the body
Open or short circuit in the sensor signal or ground circuit
Loose or contaminated electrical connector pins at the sensor
Failed PCM driver or internal pull-up resistor (less common)
Fuel contamination or extreme temperatures causing sensor misreading (indirect cause)

How to diagnose and fix it

Connect a scan tool and record freeze-frame data for P1456, then clear the code and verify it returns
Visually inspect the fuel tank temperature sensor connector and wiring for damage, corrosion, or looseness
Measure sensor resistance with a multimeter and compare to Mazda specifications for the current fuel temperature
Backprobe the sensor signal wire at the PCM and check voltage with the key on, engine off, looking for a value outside the expected range
Check for continuity and short-to-ground on the signal and ground wires between the sensor and PCM
If wiring and sensor test good, substitute a known-good sensor and recheck live data to confirm the fault
Replace the fuel tank temperature sensor if resistance is out of spec, then clear codes and verify the monitor completes

Fuel tank temperature sensor diagnostic traps

A common mistake is replacing the fuel tank temperature sensor when the real problem is a chafed wire behind the fuel tank where it rubs against the body seam.
The fuel tank temperature sensor often shares a reference voltage or ground with other sensors, so a fault in a neighbouring circuit can set P1456 without the sensor itself being defective.
On some Mazda models the sensor is integrated into the fuel pump module, so a failed sensor may require replacing the entire module rather than just the sensor.
P1456 can be set by a fuel tank that was recently overfilled or by extreme ambient temperatures, causing a temporary out-of-range reading that does not indicate a hard failure.
Always check for technical service bulletins (TSBs) for the specific Mazda model and year, as some harness routing or connector issues have known fixes.

Can I keep driving with P1456?

You can generally continue driving with P1456 because it rarely affects engine performance or safety, but avoid topping off the fuel tank excessively and have the circuit inspected soon to prevent potential evaporative system complications.

Tools that help

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Guidance is general and written for Mazda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.