I assume the tyre pressure sensors in my tyres have batteries in and one day will stop working.   My car was registered nov 2015 (fiesta mk7.5) .   From peoples experience , how long do these things last before battery fails?   And can the battery be replaced or is whole new sensor needed?  I realise replacing battery would not be easy as tyre has to come off.  

Hi Isetta, the batteries generally last 7 years.

The whole TPMS sensor is replaced as the battery is encapsulated. On some models the sensor is part of the valve stem and on others it is just attached to the valve.

Any day now then they will stop working.  It’s a bit annoying this modern stuff.  Not so bad if I could do it myself but getting tyres off is a lot of effort.  I have some tyre levers, they are fairly short motorbike levers,  I extended them by welding motorbike handlebars to each one. But it is very knackering work, I need to sit down for a few days after doing just one tyre.  Haven’t done a car tyre for a long time now

1 hour ago, isetta said:

But it is very knackering work, I need to sit down for a few days after doing just one tyre.

Just think of the poor lads at Kwik Fit they do 50 plus a day 🤣

I've never heard of anyone having to replace them,  I'd wait until the next time you need new tyres and then discuss it with your tyre fitter. Or do you fit your own tyres????

i've had to replace 1. the sensor was around £33 direct from ford and £20 for a local indie to fit. in my area the going rate was £80-£100 supply and fit. i wouldn't bother replacing until needed they may last longer than 7 years quoted as the sensor goes to sleep when not needed to save battery.  

I should just put this out of my mind and worry about it when it happens.  I don’t generally fit my own tyres, but have done on the odd occasion. I have no way of balancing them.  About 4 years ago I changed all 4 tyres on my daughter’s vw lupo myself. I got a cheap set of tyres off wheels on eBay locally.   They didn’t get high bids because most people would need to pay someone to fit them. I was lucky that the balance all seemed ok when I drove it after fitting. And lucky none had punctures. I did one each day as I find it do physically draining. 

I have an aftermarket TPMS system where the individual sensors have a CR1616 battery which is easily swapped out by the owner with no tools. After 8 years, one sensor failed 2 months ago, so I swapped out all 4 x batteries at less than £5...