What does P0451 mean?
The fuel tank pressure sensor reading does not make sense. That sensor is how the computer checks the EVAP system for leaks.
The circuit is electrically intact, but the reading does not make sense for the operating conditions. Sometimes the sensor is fine and is reporting a real problem.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Possible fuel smell
- Hard starting after refueling (with purge problems)
- No change in how the car drives in most cases
Common causes
- Sensor reading that does not match other sensors (a skewed or slow sensor)
- Mechanical problem the sensor is correctly reporting
- Restricted or leaking hose/port to the sensor
- High resistance in the connector
- Loose, cracked or wrong fuel cap
- Cracked EVAP hoses
- Faulty purge or vent valve
How to diagnose P0451
- Compare the live reading with related sensors and with known values (key on, engine off and at idle).
- Inspect hoses, ports and the connector for damage, oil or corrosion.
- Only replace the sensor after ruling out the real-world condition it measures.
- Check the fuel cap and its seal first.
- Run a smoke test, the most reliable way to find EVAP leaks.
How to fix it
- Replace the fuel cap
- Replace cracked hoses
- Replace the purge or vent valve
- Replace the charcoal canister or filler neck
Estimated repair cost
Likely repairs for P0451 run from about $100 to $350, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Fuel tank pressure sensor | $100 - $350 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0451?
Low severity
Safe to drive. It will fail an emissions test until fixed.
P0451 FAQ
What does P0451 mean?
P0451 stands for "Evaporative Emission System Pressure Sensor/Switch Range/Performance". The fuel tank pressure sensor reading does not make sense.
Can I drive with a P0451 code?
Safe to drive. It will fail an emissions test until fixed.
How much does it cost to fix P0451?
It depends on the cause. The likely repairs for P0451 range from about $100 to $350 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0451?
The most common causes are: sensor reading that does not match other sensors (a skewed or slow sensor); mechanical problem the sensor is correctly reporting; restricted or leaking hose/port to the sensor.