Unless your car is playing up, the first step is to clear the error code by disconnecting the battery for 30 seconds. If the error code comes back then look further but first make sure its not just a "glitch".
You can also remove the 20A engine fuse, in the fuse compartment under the bonnet. Same procedure, 30 seconds, but this method is just a bit easier. Also means you wont need to play around with the battery terminals, which can be risky and cause problems if you arent too experienced.