Sadly, I didn't put the new discs & pads in myself
The workshop who put in my DPs the week before last noticed my performance discs were cracked though all the drill holes. Pads were ~2/3s worn & car's done 23,000km (about 14,000 miles for the imperialists). As they already had the car in bits I've gave them the original discs I removed when the car was new & a new set of OEM pads to install. They put these in but I didn't ask them specifically about the sensors. Maybe they stuffed up here? Alarm didn't come up until a week later so I presume the sensor was at least working when they handed the car back to me.
I'll check the sensor myself. Just one on each axle isn't there? Which side on the front?