Hi everyone, I'm new to this forum, just joined. I have a 2009 Ford Fiesta Zetec 1400 cc which I have owned since almost new.  Done over 100,000 miles and my drivers seat has worn. I have a large rip in the back part which gets rubbed every time I get in and out. Looking on Ebay etc it is possible to buy a second had genuine cover but most want around £100 for that. I was quite lucky to find two complete front seats in really nice condition for just over half the price of one second hand cover.    My question is, I know I could probably change the complete drivers seat for one that I bought but am a bit worried about the way to do it, how long to have the battery disconnected etc.  My preference is to just remove the back cover from the seat and replace it with the replacement. Anyone done this ?  I am worried I might set off an airbag when I remove a cover ?   Any help much appreciated.

It's actually very hard to set off an airbag if you're not trying to set it off. 🙂 So don't worry about it.

If you decide to replace whole seat and have an OBD scanner, don't even bother to disconnect the battery. You can just remove the airbag error code after the seat replacement. 
I've removed my steering wheel airbag many times without disconnecting the battery. Never had any issues other than the airbag error code. But yes, the general suggestion is to disconnect the battery just in case. And it's not a big deal if you know your radio code etc. 

Thanks for your reply. No don't have an OBD scanner ?    Since adding this post have looked on Youtube etc for advice as well. Most say to disconnect the battery, negative first then positive and wait 5 to 20 min in case there is any residual current left in the circuit. Then unbolt the seat, disconnect the plug underneath and remove seat. Fit new seat, plug in underneath and replace battery connections positive first then negative. They say everything will still work, no need for a radio code. So still quite confusing to know which is correct.  Thanks.

11 hours ago, Roger Morse said:

Thanks for your reply. No don't have an OBD scanner ?    Since adding this post have looked on Youtube etc for advice as well. Most say to disconnect the battery, negative first then positive and wait 5 to 20 min in case there is any residual current left in the circuit. Then unbolt the seat, disconnect the plug underneath and remove seat. Fit new seat, plug in underneath and replace battery connections positive first then negative. They say everything will still work, no need for a radio code. So still quite confusing to know which is correct.  Thanks.

Well, my radio asks for a code as soon as I disconnect the battery. Maybe it's not the case with newer models. Also, If you're going to disconnect the battery, no need for OBD scanner. When the battery is connected and you unplug an airbag, it throws an error code because car's brains can't detect the airbag. This is not the case if you disconnect the battery first. Also if you're going to replace only the cover, you probably don't need to unplug the airbag anyways. 

Before disconnecting the battery, there's a button press combination on the radio, when you press certain buttons on the radio at the same time, it gives you the serial number of the radio and there are websites which you can enter that serial number and get your radio code for free. Check it out and note the serial number just in case.

Mk6 Fiesta has a radio code.  Mk7 Fiesta does not have a radio code.

Thanks everyone for the info. To help anyone else this is how it went.  I had a rip in my drivers seat cover.  Bought two used replacement seats ( bought two because that's how they were advertised )   I took apart the passenger seat to see how difficult it would be to replace a cover. It is possible but wouldn't really recommend it. To replace my driver seat I disconnected both battery terminals (negative first)  Unbolted the seat from the floor, four bolts. Disconnected the plug under the seat by pushing in the side to release it. Removed seat. Plugged in and bolted in replacement seat and connected up the battery , positive first then negative. All seems fine. Radio works, just had to reset date and time on the clock.