Parts
$30–100
P0451 — EVAP Pressure Sensor Range/Performance
SAFEIs it safe to drive? The fuel tank pressure sensor is giving inconsistent readings — emissions fault, safe to drive.
What P0451 means
The EVAP system pressure sensor (FTP sensor) monitors fuel tank pressure during the leak test the ECM runs. P0451 means the sensor's output is oscillating or jumping outside expected ranges — suggesting a lazy or contaminated sensor rather than a hard failure.
Most likely causes (in order)
- FTP sensor contaminated with fuel or debris (sits in the top of the tank)
- Sensor hose kinked, cracked, or blocked with debris
- Electrical connector corroded
- Sensor element worn or lazy from age
- Fuel sloshing causing pressure spikes that confuse the sensor
Symptoms you might notice
- CEL on
- EVAP monitor failing to complete
- no driveability symptoms
What to check first
Check the FTP sensor voltage at idle with a scan tool — it should read near 2.5V at atmospheric pressure. Lightly squeeze and release the gas cap neck while watching the voltage; if voltage doesn't respond smoothly, the sensor or its vacuum path is suspect.
Repair cost & difficulty
Labor
0.5–2 hr
Difficulty
Moderate