Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0451: EVAP Fuel Tank Pressure Sensor Circuit Performance: Description
The Evaporative Emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The function of the Fuel Tank Pressure (FTP) sensor is solely for EVAP leak diagnostics. The fuel tank pressure sensor is a transducer that varies resistance according to changes in fuel tank pressure (difference between fuel tank and outside air pressure). The ECM measures the signal voltage from the fuel tank pressure sensor, which is a reduced value of the ECM 5-volt reference. The signal voltage will read high when the pressure in the fuel tank is low (vacuum) and will decrease as the pressure in the tank increases. DTC P0451 will set if the fuel tank pressure sensor signal voltage at the ECM is above or below a calibrated voltage value considered unrational.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.