Tire not filling?

[Timberflake]

Noticed today that one of my tires looked really low so took it to the local Tesco to fill it up. All other tires fine but the one that was low wouldn't fill, any ideas what the problem could be?

I'm wondering if it's been tampered with as the cap covering the stem was missing.

[TypeDS3]

It could be a slow puncture or if it won't fill it will need looking at. I had a slow one which turned out to be screw into the tread, and got it repaired for about £12.

[Timberflake]

If it's a slow puncture wouldn't it still fill though? I was wondering if the valve core needs replacing but don't know where to get a new core from?

[Hyperkev]

Take it to get checked out at tyre shop best get valve replaced if dodgy

[DaveB]

Sounds like the valve is faulty - possibly as a result of the missing cap.

[Timberflake]

I'm going to give Citroën Assist a call tomorrow and see if it's covered under my lease agreement. Failing that, I've got a place no about 100m down the road but will need to put the spare on first

[Timberflake]

So Citroën Assist wanted £120 plus VAT just to come out as punctures aren't covered! Found a local garage that was open so jacked the car up to put the spare on and found the problem, a massive piece of metal had skewered the tire!