As above. I have checked everything over, no obvious problems. It runs ok then stops working, then its starts working again.

The display is clear, so its not the battery there. Battery in the sender unit perhaps?? Any suggestions, thanks……….

Most likely its the sender battery (always has been on mine in the past) but on mine the display has been intermittently dimming then comes back on but with no signal so I suspect the main unit battery is a bit flat.

Wireless = unreliable in my experience.

Not at the limit of range between sensor and head unit are you? Mine wouldn't reach the rear wheel.

The sender unit makes a very quiet clicking noise when the magnet passes it, sometimes if i don't have the magnet in the correct position it doesn't always pick up. It does this even when the battery is dead, so if it is still making the clicking noise, and not sending a signal, good chance the sender battery needs changing.

I have two of these at the moment .
One on the road bike and one on the XC bike, both can be quite sensitve to the gap between the wheel magnet and sensor.

other than that ive found them to be totally reliable

never had a problem with mine, but GPS devices can interfere with the signal and stop them working if they're too close, so if you have one on your handle bars / in you bag etc, it may cause a problem.