Whilst travelling in Ireland on holiday recently, I noticed a warning appearing on the dash display, informing me that the battery in my key fob was getting low. I didn't do anything about it until I got back to the UK, when I got a new battery installed at a local key cutting/boot & shoe repair shop. The battery was checked prior to installation and the guy also had an RF detector box which showed that the fob was transmitting. However, when I got home and tried to open the car (2013 Mazda 6 SportNav), I found that none of the buttons worked. So back I went to the shop, where the guy took out the battery, tested it, cleaned the contacts and checked once again that the fob was transmitting. Back home again and still no joy.
Next obvious step was to Google the problem. This returned numerous posts and videos showing how to 'reprogram' the fob. Most of these involved opening and closing doors whilst turning the ignition key on and off (the 2013 Mazda 6 has keyless ignition, so that was a dead end).
Eventually, in desperation, I phoned the main dealer where I bought the car. I explained the problem to a guy in the service department who told me that this was not unusual, since once the battery in the fob drops below 3.6 volts the program memory cannot be sustained whilst the battery is changed. 'So what do I do now?', I asked innocently. 'You'll have to make an appointment and bring the key and your spare in to us. We have a computer program which we run to duplicate the settings from a working key to a non-working key. This takes between thirty and forty minutes and costs £40 + VAT'. As you might expect, this was met by a stunned silence from me (I've been programming for many years), followed by a rather loud, 'You must be ******* joking!' 'No said the guy. It's a lengthy process reprogramming one of those keys, so we have to charge that'. 'I'll get back to you', was my reply.
So then I phoned the guy at the local key shop and asked him how much he would charge to reprogram the fob. 'I don't need to', he said', 'What Mazda have told you is complete boll***s. Those keys almost never lose their program and certainly not in a situation like this. All that's wrong with it is that it's somehow lost it's registration with the car. This should be simple to fix. You just need to get the instructions for your particular model'.
At that point, I did the unthinkable: I got the manual out and looked up 'Keys' in the index. It took a few minutes, but I eventually discovered a section named 'Key Suspend Function' (page 3-9 in my manual) . This describes a situation where a key can be temporarily disabled if the key has been accidentally left in the vehicle. Whilst this was not what happened in my case, I was willing to give the 'Restore' procedure a try. This was pretty simple: All I had to do was sit in the car with the non-operational key, plus a working second key, then press any button on the non-working key and depress the clutch pedal until the KEY indicator displayed in green. It worked first time.
The moral of this story is fairly obvious: Listen to the Wise Old Shoemaker before you get conned by a dealer; and as I said at the beginning - RTFM!
