If you replace your car's remote entry battery, you may need to reprogram it so that your car's computer recognises its signal. Programming instructions vary between make, model and year, but what they have in common is a long sequence of tasks--inserting the ignition key, locking doors and the like in a precise sequence. Your car's owner manual might not list the programming steps, but instead just refer you to your nearest dealership. They may charge you £32 to £65 for the service, though, so your goal is to find the instructions.
Look your car up on Programyourremote.com first. This expanding repository of almost three dozen makes splits out programming instructions by make, model and year. Start off by clicking the make of your car in the left column, and then click on your model in the subsequent list. Then click on the year on the next page, and the info you need will pop up.
Look up your car's manual on Ownersmanualsource.com. This somewhat less comprehensive repository of 12 leading makes also breaks down by make, model and year. Your manual may have the needed programming instructions. Just click on the make of your car at the top of the screen. You'll be sent to a list of models. Click on yours to be sent to a list of manuals broken out by year.
Call various dealerships. A representative at a dealer may give you the instructions over the phone. Since you can find dealerships across the country online, there's no reason to confine your search to local retailers. When you call, it's important that you know the year of the model, since instructions vary widely by year. The make, model and year should be enough for the dealer to go on.
Sometimes, the fob is manufactured without giving the owner the ability to program it, and there's no way to get around having the dealership do it for you.