False Alarm

[trevorpitt]

I wonder whether anyone can offer advice on an annoying fault. Over the last few days my Z4 (2.0SE '55) has developed the habit of sounding the alarm about five minutes after parking and locking the car. When I unlock and relock it then stops, but the same happens every time I park. Is there an obvious remedy?

 

[ovrkll]

Bonnet sensor

 

[trevorpitt]

I've tried the bonnet sensor, sprayed it with WD40 - doesn't work!

 

[Wondermike]

Is it still in warranty, just? The dealer will be able to tell you which sensor it is, still the bonnet is the most likely one though.

 

[cj10jeeper]

I had the same fault last wek - they all shouted 'bonnet sensor'. I removed it (easy enough to do) ran if for 3 days with no bonnet sensor - no alarms. Fitted the new one whne i tarrived - no alarm. Guess what - it was the bonnet sensor!!! Confimred by the parts guy at the local stealership who tells me the only item he ever supplies alarm parts for is faulty bonnet snesors......

 

[eurgain]

I've tried the bonnet sensor, sprayed it with WD40 - doesn't work!

Have you tried disconnecting the bonnet sensor altogether? (Remove the electrical connector.)

That was certainly the problem with my car, and I believe that it is as common as a rusted bonnet
cable (i.e. very usual on any Z4).

If the alarm stops sounding when you pull the wires, you know what the problem is. However the
car will accumulate multiple events in the fault memory, which could hide real problems
being logged, so you should really sort the problem.

WD-40 is no good if the switch is faulty. Spray with a switch cleaner such as RS Contact Aerosol
Cleaner or Super Servisol. Orjust get a new one (they are not too dear).

A

 

[dgm]

I've had the alarm going off intermittently for a few weeks, BMW state the fault has been logged as the tilt sensor. As usual with the Z4M I'm having to wait for the part to be delivered but worth considering as the cause of your problem Trevor along with the bonnet sensor.

 

[trevorpitt]

Thanks, fellas - the false alarm became intermittent, OK one day then sounding several times the next when parked. Eventually took it to the dealer, who diagnosed faulty bonnet sensor, but didn't have the part in stock because 'it is such a rare occurence on Z4s'! So several visits later (70 miles round trip and petrol approaching £6 a gallon!) all is now quiet. Except that today the tyre sensor came on ... this is not the most reliable car I've ever owned!

 

[Wondermike]

...but didn't have the part in stock because 'it is such a rare occurence on Z4s'!

Did he look like this as he said it



Tyre monitor might just be a loss of pressure rather than anything serious, but check them all as you may have a puncture.