Fuel tank pressure sensor reading erratically.
P0451 — also written PO451, P 0451, 0451 — is the OBD-II code for evap fuel tank pressure sensor range/performance. Same code, same fix: this page covers every spelling of it.
This one's all about the brain of the car getting confused by the air pressure inside your petrol tank. It’s a classic headache on older Vauxhall Corsas and Astras where the sensor gets tired or the wires rot through.
P0451 is a emissions fault code, typically costing £90–£350 to put right in a UK garage.
What P0451 actually feels like to drive
- The engine management light is staring you in the face, but the car drives perfectly fine.
- A slight hiss or 'whoosh' when you open the fuel filler cap after a long run.
- The petrol pump at the garage keeps clicking off every two seconds like the tank is full when it's empty.
- Fuel gauge acting a bit erratic or dropping faster than normal.
- A faint smell of petrol vapours around the rear wheel arch after parking up.
What causes P0451?
- Failed sensor
- Wiring fault
UK vehicles that throw P0451 most often
- Vauxhall Corsa D/E 1.2 & 1.4 (2006-2018)
- Vauxhall Astra J/K 1.4 Turbo (A14NET engine)
- Ford Fiesta Mk7 1.25 Zetec (2008-2017)
- Ford Focus Mk3 1.0 EcoBoost (2012-2018)
- Nissan Qashqai J11 1.2 DIG-T (2013-2018)
- Fiat 500 1.2 Fire (2007-present)
How P0451 is fixed
- Replace tank pressure sensor
- Repair wiring
The P0451 misdiagnosis that wastes money
I’ve seen too many lads just jump straight to the sensor or, worse, start replacing expensive charcoal canisters. More often than not on UK roads, it’s not the sensor itself that’s died—it’s the wiring harness right near the rear axle. Road salt from our winters gets into the loom and rots the wires thin. You get a 'ghost' reading where the sensor looks like it's working but the voltage is jumping all over the shop. Check the connector pins for green crusties before you spend a penny on parts.
What a UK garage should charge for P0451
You're looking at about £50 to £80 for a proper diagnostic plug-in to see what the live data is doing. A genuine Bosch or Delphi sensor usually runs between £40 and £120 depending on the car. Labour is the wild card; if it’s a Corsa, I can swap it in 30 minutes (£40), but if the tank has to come down on a Qashqai, you’re looking at two hours (£150+). All in, an indie garage will charge you £150–£250. Main dealers? They’ll double that without blinking.
P0451 repair cost in the UK
Most P0451 repairs land between £90–£350 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0451
If a garage tells you that you need a new fuel tank because the sensor is 'integrated,' tell them to hang on. On many Vauxhalls and Fords, you can actually get to the sensor via an inspection hatch under the rear seat or by slightly lowering the tank—you don't need a £1,000 tank assembly. Insist they do a 'live data' sweep. If the pressure reading doesn't change when they pop the petrol cap off, it's a dead circuit or a blocked breather, not a major fuel system failure. Also, check your fuel cap seal—it's a £10 fix that solves 'leak' codes often confused with this one.
Can you drive with P0451?
Yes.
Urgency: low.