P0451
Evaporative Emission System Pressure Sensor Range/Performance
The fuel tank pressure sensor reading is implausible — for example, fluctuating signal, noise, or values that do not respond to known pressure events such as a key-on tank refill.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Common causes
Ordered by how often each turns out to be the cause.
- Tank pressure sensor drifted/noisyCommon
- Sensor element aged beyond calibration windowLess likely
- Sensor mounting loose - signal dampingLess likely
Parts involved
- Fuel Tank Pressure Sensor
- Sensor Wiring
P0451 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.