Morning all,

Just a question about how the tyre pressure monitor functions. If I go into the menu and 'hold OK to reset tyre pressure monitor' will the warning and warning light come back on if the tyre pressures still aren't what they're supposed to be? Or does it just calibrate it to the current pressure?

Basically, I got the warning light just now, stopped at a petrol station to fill up but could not find a puncture/nail or anything obvious on any of the tyres. Also, none of the tyres stood out from the others with really low pressure. In fact, all tyres were low with 24 rear and 28 front (recommended is 26 rear and 33 front). This is odd because I got it serviced by Ford on friday and have done about 300 miles since so unless they've filled them low and it's taken my car 5 days to realise, I can't find the problem. I've reset the monitor after filling and I'm now parked up at work so I'll go out in a few hours to check if the warning comes back on. 

Chances are, the garage didn't bother checking the tyre pressures. Many mechanics are lazy swines. Many garages also force through as many cars as possible, without leaving enough time to do all checks that they charge you for.

The fact that all tyres released pressure at the same rate is good. Tyres naturally lose pressure. Presumably when you topped up, the light went out? If not, reset the monitor. It then remembers the new pressure and monitors against that.

At least this is my understanding of how such systems work. They can't have a certain pressure memorised because you're meant to adjust it depending on what you're doing - such as carrying a heavy load.