P2451 code meaning
EVAP System Switching Valve Stuck Closed
Powertrain system Generic code P24xx codes Check engine light
What P2451 means
P2451 is the reverse fault of P2450: the evaporative system switching valve will not open when commanded, so vapor or test pressure cannot pass where the system expects it. It shows up mainly on vehicles with a sealed, pressurized fuel tank, such as plug-in hybrids. Mazda's CX-90 and CX-70 PHEV can set it together with P0451, P2422 and P0441; the bulletin suspects the tank pressure sensor or the tank shutter valve and replaces the shutter valve plus the vapor hose that carries the tank pressure sensor. Ford's C-MAX and Fusion hybrids and Energi models listed P2450 and P2451 in a bulletin warning that a software conflict could falsify a pinpoint test unless the fuel door was opened at a set step. A blocked valve can also keep the tank from depressurizing before refueling. Circuit faults of the valve are P2418 to P2420.
P2451 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P2451
- Malfunction indicator lamp on
- Fuel door or refueling release slow or not working on sealed-tank hybrids
Common causes of P2451
- Most likelyTank shutter or switching valve stuck closed
- PossibleFuel tank pressure sensor giving wrong values to the monitor
- Less likelySoftware or test-sequence issue (fuel door handling on some hybrids)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP switching valve
What each part of P2451 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 51 | The exact fault in that area. |
What to do next
- Note P2451 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2451
What does P2451 mean?
P2451 means "EVAP System Switching Valve Stuck Closed". P2451 is the reverse fault of P2450: the evaporative system switching valve will not open when commanded, so vapor or test pressure cannot pass where the system expects it. It is a generic code, so it means the same on every make.
Is it safe to drive with P2451?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2451 fail an emissions test?
Yes, it can. P2451 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2451 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P2451 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.