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P0451: EVAP pressure sensor range or performance problem

The sensor measuring vapour pressure in the fuel tank gives values that make no sense. Could be the sensor, its connector or a fuel cap not sealing.

Code P0451 at a glance
CodeP0451
SystemEngine and transmission
GroupP04xx, Emissions control
TypeGeneric: it means the same on every make
Can you keep driving?Yes, no rush

What P0451 means

The tank pressure sensor helps the ECU check the vapour system for leaks. Its signal is within the electrical range, but does not match what it should see (for example it does not change when the cap is opened, or moves when it should not).

Most common causes

  • Fuel cap not closed properly
  • Sensor hose loose, blocked or full of water
  • Corroded sensor connector
  • Faulty fuel tank pressure sensor
  • Stuck vent valve affecting the pressure

Symptoms

  • Engine warning light on
  • Other related EVAP codes
  • No change in how it drives

Can you drive with P0451?

Yes, no rush It does not affect the engine. You can drive normally and have it checked when convenient.

How to check it

With the ignition on, watch tank pressure on your reader and open the fuel cap: the reading should drop to zero. If it does not move or shows odd values, the sensor or its hose is at fault.

How to read and clear P0451 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0451 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0451 is a generic code, so it means the same on any make, for example on Abarth, Citroën, Hyundai, Mini, Seat, Volvo. See what Final OBD does on your car in makes and models.

What does code P0451 mean?

The tank pressure sensor helps the ECU check the vapour system for leaks. Its signal is within the electrical range, but does not match what it should see (for example it does not change when the cap is opened, or moves when it should not).

Can you drive with P0451?

It does not affect the engine. You can drive normally and have it checked when convenient.

How do you clear P0451?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0451 comes back.