Tyre deflation warning constantly coming on.

[ratherbecycling]

My Jazz triggered a tyre deflation warning. Checked 4 tyre pressures - all were within 0.5psi of what they should be. Reset the warning. Drove about 50 miles at max 60mph. Deflation warning triggered again.

Rechecked all 4 tyres (when tyres had cooled) with same digital pressure gauge, and all were exactly the same as they were two days previously. Reset it again

I did have a sticky brake calliper replaced earlier in the year, but have since regularly checked that none of the wheels is getting hot.   

Plus - before the calliper was replaced and the wheel got hot, the hot wheel did NOT trigger the deflation warning. (That makes sense actually, because the tyre circumference would have IN-creased slightly with the IN-creased pressure, and the Jazz manual specifically says it senses a reduction in tyre pressure, not an increase)

[Basil]

Do you have matching tyres i.e. make and amount of wear ?

[Webley]

Scan for ABS codes.
They may have damaged the wiring when changing the caliper causing an intermittent fault.Ask me how I know.
As previously mentioned having different types of unevenly worn ones can also cause this.

[BadgerMk3]

Plus - before the calliper was replaced and the wheel got hot, the hot wheel did NOT trigger the deflation warning. (That makes sense actually, because the tyre circumference would have IN-creased slightly with the IN-creased pressure, and the Jazz manual specifically says it senses a reduction in tyre pressure, not an increase)

That's true, but you may have to look at it from a different angle.

Obviously I'm not privvy to the algorithms used, but based on knowledge gained on with another car brand, the hotter wheel itself may not trigger the deflation warning, but the increased difference in pulses between that and the other cooler wheels may well do.

When I had my Jazz, I regularly checked and adjusted the tyre pressures accordingly. Each time I reset the deflation system and drove a good few miles over varying road conditions and speeds to give the system a wide range of reference data.

During my ownership I replaced the tyres once, as a full set. I don't recall suffering the same symptoms that many seem to do on here.