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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 21624
Experience:  BEng hons Mech engineering, in auto industry 22 years
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hi, ive a slight problem. my air-bag light stays on constanltly

Customer Question

hi, i've a slight problem. my air-bag light stay's on constanltly i've had a diagnostic test for it to say that the problem is the Passenger side pressure mat sensor. can you please tell me is it a easy job for me to do myself or can you explain what i have to do or do i take it to bmw garage to carry out the repair thanks.
Submitted: 3 years ago.
Category: BMW
Expert:  Matt replied 3 years ago.
Hello

the pressure sensor is just under the seat cushion so when a passenger sits in the seat the Airbag controller knows to enable the passenger airbag


its possible to replace at home but you do have to remove the seat from the car and then get the seat cover off the frame to access the sensor pad

but before going that far I'd 1st get some switch / contact cleaner spay and locate the sensor connector under the seat

with the ignition turned off try disconnecting this sensor connections and spraying both sides with the contact cleaner and then connect and disconnect the sensor plug several times to try and scrub the contacts clean of any built up corrosion

as its quite possible that its a just a poor connection on the sensor connector
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Customer: replied 3 years ago.

hi matt thank you for the advice you gave me to try and rectify the problem i have. I took the car to a garage for them to try and sort the problem,now the other problem was my engine managment light which was on as well as the air-bag light.


the engine light he done the test ,and said it had a air leak he done a smoke test found a leak and rectify it plus got a by-pass switch for the air bag light rectified that, got car back drove for a couple hours only to find that both faults have reappeared. taking car back don't know until end of week.will let you know the out-come mick

Expert:  Matt replied 3 years ago.


Hello Michael

also worth checkig for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.

this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst

The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers

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