Faulty tyre pressure warning system?

[c63chris]

Took my lot to visit my parents this weekend some 200 odd miles away. Blatting back doen the M4 this morning the dash goes red and a message appears telling me to check my tyre pressures. Pulls into the next services as I had run over crash debris earlier on and everything looked fine and couldnt see or feel anything wrong with the tyres. 100 miles to home, no problems, parks up and lets the tyres cool down. When I checked the pressures they are all ok Have reset the run flat indicator as the car asked. Anyone else had spurious warnings? At the time it went off I was 'keeping up with the flow' of traffic down in the outside lane of the M4 so not doing anything lairy Could understand the ABS getting confused in other situations but just cruising in a straight line

 

[Simon_M]

I had one false alarm once in the CLK. Much like yourself I was pressing on while driving the M23. Alarm popped up and I pulled off, as the car was parked up with full lock the tyre looked deflated so I started to remove it. Once it was off I decided it looked and felt OK, I put it back on and reset the warning system (figuring if it was still loosing pressure it would go off again) and it was fine for the rest of the journey.

As these use the ABS sensors, I suspect the tolerances are very low. I would just keep a watchful eye open.

S

 

[et0609]

Its happened to me a couple of times. Each time, no visible loss of pressure. According to my dealer, a very small drop in pressure will set off the system.

 

[jefrs]

Is the clue in "blatting down the M4"?

Had you raised the pressures for fast driving? - if not then it may have considered the pressures a bit low.

 

[c63chris]

Is the clue in "blatting down the M4"?

Had you raised the pressures for fast driving? - if not then it may have considered the pressures a bit low.

No I hadn't but I thought it doesn't read pressure only uses the ABS sensors to detect a wheel turning at a different speed the logic being a drop in pressure changes the circumference and therefore the rotational speed? If they are all low then the system wouldn't trigger?

 

[jefrs]

No I hadn't but I thought it doesn't read pressure only uses the ABS sensors to detect a wheel turning at a different speed the logic being a drop in pressure changes the circumference and therefore the rotational speed? If they are all low then the system wouldn't trigger?

Which would happen when blatting the M4 with flat tyres.

 

[ranjo]

On a similar note can anyone tell me how to reset the run flat indicator on a e220 cdi please