MOT Airbag question

yes. its a hard fail.

'Airbag obviously inoperative' (i.e. warning light on) is a major and will result in a fail.

Years ago I had an airbag go off due to a wiring issue (basically the garage that fitted the telephone kit managed to catch a wire, which shorted about a year later).

Scared the living crap out of me, as I was driving at the time - luckily it was the passenger airbag, my ears were ringing for hours.

It also destroyed the dash as it expanded through...

Managed to get it booked in for Friday, luckily they have time to look at warning light issue before MOT.

"looking at" a warning light and solving it are two different things, unless its just an old fault that can be cleared. If I were you I'd plan an alternative for vehicle access for the weekend

Any warning light is an automatic fail on the MOT, regardless of how insignificant the fault causing it is.

The airbag light will also probably detect faults in the seatbelt pretensioners (like a shotgun sized cartridge in a piston that yanks the seateblt tight at the same time as the airbag deploys).

They're a weak link on a lot of cars where the wires come out the floor and into the seat. Getting bent back and forth each time it's adjusted, and wacked with anything jammed under the seat.

DISCONECT THE BATTERY AND WAIT 20MIN BECAUSE IF IT GOES OFF IT WILL TAKE YOUR FINGERS WITH IT. Then disconet and reconnect the plugs under the seat a few times and see if that clears it.

The systems work by measuring the resistance of the circuit with a tiny current so if the connection is borderline it will show a fault. My Berlingo used to do it almost monthly but I had to take the seats out fairly regularly so I was loath to solder the wires properly.

Notaspoon, that is interesting. I've only owned the car a couple of months, I bought it off a friend who is a bit of a clean freak and he took the seats out to shampoo the carpet before selling it to me.

my passat of that vintage had a dodgy connection under the passenger seat. put the seat too far back and the airbag light would come on.

clear it with a code reader and it wouldn't come back on until you pushed the seat too far back again.

Another common candidate is the clock spring / slip ring under the steering wheel.

Another common candidate is the clock spring / slip ring under the steering wheel.

Also true, but I'd put it in 2nd place as it's relatively safe from mechanical damage and with the caveat that any attempt to examine it will probably break something as they're full of teeeny tiny little connectors so it's the last one I'd check when I was sure it wasn't the seats. And I'd have the replacement from a scrappy to hand so I just had to swap them over rather than attempt to take the cover off.

And I’d have the replacement from a scrappy to hand so I just had to swap them over rather than attempt to take the cover off.

Well yes.

I had an airbag warning fault on daughters clio which was fixed with checking loose wire under passenger seat (car self diagne=osed on start up). On the Citroen relay van I had to send the module in for a reset to clear the fault which was £30-40

he took the seats out to shampoo the carpet before selling it to me.

Bet one or both of the seats have not been plugged back in. Also I had a recurrent airbag fault which was solved by popping out the passenger key operated switch (often hidden in the end of the dash so it's covered when the passenger door is shut) and cleaning the contacts on the back of it.

Just going through this with the little Aygo we've got for daughter. Airbag flashed up after going on a rough farm track. Managed to clear it, and all clear until the last week. Keeps coming up at random. All connectors checked and 'cleaned' with electrical contact cleaner (passenger and both side air bags) - going to book it in as suspect it's the clock spring - well known to fail on Aygo's.

Many code readers can not clear airbag faults (workshop ones can and diagnose it). I get an occasional light with my Nissan (it is 20 years old) and it's usually the drivers seat, as the connector is right in line with people's feet as they get in and out the back. With many Nissan's though, they have built in diagnostics, and some timed turns of the ignition, will get the system to flash the code. Off one goes with contact cleaner, plugs back in, and you then repeat a sequence for the system to rescan. If no errors, it clears. This isn't on the Toyota though, so unless a battery disconnect clears it, it's the garage for me.

Faults are nearly always with the blooming connectors playing up. Oh I do need to look at the passenger air bag 'off' switch too - could be that as well.

My mondeo gets the airbag light due to the underseat connection. Typically if I push the seat all the way forward it'll trigger it. Put chair in normal position and plug and unplug will fix it. Certainly worth a try.

My old passat did this to me. Funny reading what others have said as mine happened just after I cleaned the car and hoovered under the seats so I must of hit something under there. Never found out as it was traded in shortly after.

It looks like he has plugged it back in but wrapped the cable under, rather than over a seat bar. This means that when the seat has been pushed right back it has pulled the connector away from the bracket which is meant to hold it. This will explain why the fault light didn't come on immediately after buying it. No obvious damage though so I've fiddled with it, shoved it around a bit and I'll reconnect the battery and see if that has fixed it in a bit.

Even if I have not fixed it, I am pretty sure I have identified the problem

I've had an issue in the past with a Ford, it had a pressure sensor in the front seats that is used to manage a 2 stage airbag deployment, ie more charge for a heavier person. If this gets damp, for example after wet cleaning then the airbag light comes on until it's properly dried out. Guess how I found this out.....

Guess how I found this out…..

You heard a particularly funny joke on the radio then the warning light came on?

Even if I have not fixed it, I am pretty sure I have identified the problem

from memory, on a vw the light won't clear even if you fix the problem. it needs resetting with a code reader.

Hasn't worked, light still on. I am confused though, by disconnecting and reconnecting the battery I have in effect turned it off and turned it on again. How on earth has this not worked?

The only other way I know how to fix things is with gaffer tape or zip ties, neither of which seem to be the right tool for this job.

Airbag lights nearly always need to be reset by a code reader.

If anyone wants to bodge it here you go - take the SRS bulb out of the dash. This will only be an advisory come MOT time believe it or not. Obviously you will still have the airbag fault and it might mean the whole system is disabled so I cannot condone anyone doing it (apart from the sod who sold me my last Z4...)

Most safety and emission system faults are stored to a permanent memory. So key off/battery off won't clear it.
They've been doing that (with varying levels of success) since the late 90's.
Some you can clear by shorting two pins on the ECU with the memory. Get the wrong two pins and you'll need a new ECU.
Most, as stated above, you'll need a proper code reader or the "full" diagnostics tool from an authorised workshop.

whats the car? some need a certain number of ignition cycles after the code cleared for the light to clear. Worth grabbing a cheapo code reader with next-day delivery off amazon (<£20) to see if it can clear it, I used to be able to clear my 2010 vauxhall that way

Car is a 56 plate Polo

Most readers can't clear the Airbag. The Aygo isn't even powering my reader or my son's VW one - no light, so can't even check. It works in my car.

Got battery negative disconnected for an hour now. If no joy, I'll leave for 24h.

My old punto would clear with a cheap code reader.

My 2014 Iveco van cleared but it needed a couple of restarts/short drive to decide it was happy with the resistor I substituted for the middle seat.

With side airbag equipped cars I've had two with a "nick" in the door loom wiring. I think at least once the garage didn't even charge.