Vent valve circuit open.
P0447 — also written PO447, P 0447, 0447 — is the OBD-II code for evap vent control valve open. Same code, same fix: this page covers every spelling of it.
P0447 means the ECU can't 'see' the vent valve because the electrical circuit is broken—usually due to a snapped wire or a burnt-out solenoid coil. It's a common nuisance on Vauxhalls and Nissans that spend their lives in the wet.
P0447 is a emissions fault code, typically costing £60–£260 to put right in a UK garage.
What P0447 actually feels like to drive
- Engine management light (EML) glowing amber on the dash.
- Absolutely no change in how the car drives or pulls.
- A slight smell of petrol fumes around the rear wheel arch when parked up.
- An automatic MOT fail if the tester sees the EML lit.
- Fails an emissions test if the vent is stuck in the wrong position during the purge cycle.
What causes P0447?
- Failed vent solenoid
- Wiring break
UK vehicles that throw P0447 most often
- Vauxhall Astra J 1.4 Turbo (A14NET) 2009-2015
- Nissan Qashqai 1.6 Petrol (HR16DE) 2007-2013
- Ford Fiesta 1.25 Zetec 2008-2017
- Vauxhall Corsa D 1.2/1.4 (A12XER) 2006-2014
- Mazda 3 1.6 MZR 2009-2013
- Toyota Yaris 1.33 VVT-i 2011-2017
How P0447 is fixed
- Replace vent valve
- Repair wiring
The P0447 misdiagnosis that wastes money
I’ve lost count of how many times I’ve seen brand new petrol caps fitted or expensive charcoal canisters swapped out for P0447. It’s a waste of money. Because the code says 'Open', people think the valve is stuck open, but it’s actually an electrical term meaning the circuit is broken. Nine times out of ten on UK roads, it’s not even a faulty valve—it’s the thin wiring near the rear axle that’s snapped or corroded thanks to the road salt we use up here in Scotland.
What a UK garage should charge for P0447
A basic diagnostic scan to confirm the code will set you back £50 to £80 at a good indie. If it’s just a broken wire, I’d usually charge an hour’s labour (£60-£90) to solder and heat-shrink it. If the solenoid is genuinely dead, a decent aftermarket part from Euro Car Parts or GSF is usually £60-£120, plus half an hour to fit. A main dealer will likely want £250+ just for the part and a shiny coffee.
P0447 repair cost in the UK
Most P0447 repairs land between £60–£260 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 P0447
Before you let a garage bill you for a new solenoid, insist they do a 'continuity test' on the loom. If they’re worth their salt, they’ll use a power probe to trigger the valve manually. If you hear it 'click' but the ECU still sees an open circuit, the fault is in the wire, not the part. Also, ask them to check the connector pins for green crusties (corrosion); a quick clean with contact cleaner often saves you buying a £100 Bosch valve.
Can you drive with P0447?
Yes.
Urgency: low.