Airbag SRS fault 02 20

[Zentrum]

Hi guys I've a recurring airbag SRS light that keeps coming on and going off at random intervals. I bought the B800 scanner and reset tool to try and troubleshoot but I can't get the light to stay out. The code I keep getting is 02 20 which is the sensor, side airbag left line fault. I removed the seat and left hand door card and checked the wiring visually as far as I could and also removed the plug on the side airbag sensor (Temic 65778381564) It all looks ok to me. When I put it back together the airbag light goes out when the ignition is switched on but soon comes back on again within say 30 to 60 seconds. It can then go out again even if I'm not sat in the car. I tried jiggling all the various wires and plugs under both seats to see if I can get the light to activate due to suspect wiring but there isn't any obvious related immediate - light on - event. I'm at a bit of a loss at the moment. Could the fault be with the sensor itself? I thought about swapping the left and right sensors over to see if that will get me a new fault code. Any thoughts would help.

[rf900rkw]

I'm not sure why you are inside the door. The side impact sensor is mounted to the rail under the seat. Anyway, two things I would try.

Since your car is RHD, might try the right side impact sensor.

Try INPA or some other SRS capable scanner. There have been errors discovered in the Peake booklet, which the B800 "borrowed".

- - - Updated - - -

Swapping sensors would be a good test. Also purposely leave one and then the other unplugged and make sure the codes set match up.

[Zentrum]

Thanks for the reply rf900rkw. I decided to remove the door trim to check the wiring for any shorts but it all looks ok to me. My next move is to lift up the carpet to check the wiring loom under there but I'm not sure how to remove the plastic sill cap, any ideas how that comes off.

[emoore924]

Just an additional thought, if you're messing about with the airbag or sensor squibs (wiggling wires, checking connections) I wouldn't do that unless you've disconnected the battery and let the capacitors discharge for at least 10 minutes. That way you reduce the risk of unanticipated airbag deployement, read: BANG!)

[Blacklane]

Thanks for the reply rf900rkw. I decided to remove the door trim to check the wiring for any shorts but it all looks ok to me. My next move is to lift up the carpet to check the wiring loom under there but I'm not sure how to remove the plastic sill cap, any ideas how that comes off.

Starting at one end, pull straight up. If you break one of the plastic clips, they are readily available. Part number 51478399492, Item 7 here: http://www.realoem.com/bmw/showparts...46&hg=51&fg=55

[Zentrum]

Thanks for that emoore924, good idea, I'll disconnect the battery and I'll have a go at lifting up the sill trim now, thanks Blacklane.

[Zentrum]

Turns out it was the side airbag sensor. Swapping it over to the other side highlighted new fault codes which had swapped as well. The faulty sensor looked a little corroded which might have caused the failure if it had got wet at some point in the past. Interestingly the airbag light was fixed (ie stayed off) by just swapping the new sensor in place without having to delete the fault codes. I of course also deleted the codes after I finished the job.