Airbag light on mercedes w204 c class

Wilhelm

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Hello, I have a problem with my car. (2011 W204 c220 estate) There was a error message the circular display saying there was a malfunction on the front left airbag. The light for the airbag under the rev counter periodically turns on when driving for around 2 to 30 seconds and then goes out. It's really random though when it come on but the error message in the circular display is always on. I'm guessing it's just a lose connection somewhere and the error message needs to be cleared. I have checked the fuses and they seem to be all OK. Anything else I could try?
 

richard

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Your probably guessing wrong :)

More likely to be the passenger seat sensor mat (in the seat), but you are only going to really know with a diagnosis session which will tell you which component (for instance it could be the airbag, or wiring, etc etc)

Cheers

Richard
 
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Wilhelm

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OK thank you for letting me know. I will do this then.
 
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Wilhelm

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Your probably guessing wrong :)

More likely to be the passenger seat sensor mat (in the seat), but you are only going to really know with a diagnosis session which will tell you which component (for instance it could be the airbag, or wiring, etc etc)

Cheers

Richard
So a few months down the line I get it checked last week and it was the seat mat sensor like you said. You're a genius!!!! Thank you so much. Is this a common problem?
 

wongl

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I am having/had a similar problem in R172 - the strange thing is that I had the red air bag symbol flashed up on the dash for about 20 seconds with a message popping up in the central console. But after 20 seconds or so, the red airbag symbol disappeared and I am left with the message in the console.

The stranger thing is if a passenger sits on the passenger seat, the amber warning message lights up saying passenger airbag is active. So it seems everything is functioning as it should be except for the warning message. I cannot clear this error with my iCarsoft because as soon as it is cleared the error reappears. I am going to try clearing the code with Xentry but I am not too hopeful.
 
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Wilhelm

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I am having/had a similar problem in R172 - the strange thing is that I had the red air bag symbol flashed up on the dash for about 20 seconds with a message popping up in the central console. But after 20 seconds or so, the red airbag symbol disappeared and I am left with the message in the console.

The stranger thing is if a passenger sits on the passenger seat, the amber warning message lights up saying passenger airbag is active. So it seems everything is functioning as it should be except for the warning message. I cannot clear this error with my iCarsoft because as soon as it is cleared the error reappears. I am going to try clearing the code with Xentry but I am not too hopeful.
Yeas I had a similar problem with the light coming on and off and the central message always staying on. Obviously it is working 'part-time' and I think there must be some problem that only occurs periodically so clearing the code might temporarily solve the problem but as soon as the car notices the error the code will be saved and the central light will stay on until the code is cleared again. Depending on the code and where the problem is it might be worth looking for maybe a loose connection such as a cable or a fuse (unlikely)
 

wongl

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Yeas I had a similar problem with the light coming on and off and the central message always staying on. Obviously it is working 'part-time' and I think there must be some problem that only occurs periodically so clearing the code might temporarily solve the problem but as soon as the car notices the error the code will be saved and the central light will stay on until the code is cleared again. Depending on the code and where the problem is it might be worth looking for maybe a loose connection such as a cable or a fuse (unlikely)
I am planning on replacing the passenger seat mat sensor this coming week on my R172 (2012 model). Does anyone have the workshop pdf by any chance to see what the official steps are?
 

E55BOF

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I hope it's not like the R171. You can't buy the mat separately, you have to buy the entire seat cushion assembly, and in my colour scheme that's over £1000...:oops::oops::oops:
I had it coded out.
 

Flyinspanner

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Go on eBay and buy an emulator, fit and get the fault code erased on star, - no more light. They are about £10 and super easy to fit. You don’t disturb the seat :rock:
 

Wolfie1

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I would adjust the pin tension on the plugs first on that seat before replacing anything, free to do and quite high up the list of probable causes
 

wongl

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I hope it's not like the R171. You can't buy the mat separately, you have to buy the entire seat cushion assembly, and in my colour scheme that's over £1000...:oops::oops::oops:
I had it coded out.
Already sourced a brand new seat mat sensor from Newcastle MB via their eBay store using my VIN number. I then used a consolidated shipper to ship to HK. All in under £200 whereas the cost for the same part from MB HK is over £1000.
 

wongl

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Go on eBay and buy an emulator, fit and get the fault code erased on star, - no more light. They are about £10 and super easy to fit. You don’t disturb the seat :rock:
SRS emulators are okay but not for me. I want to keep all functions working as from the factory (the only exception is the smartop device since this adds some very useful features to the car while integrating so seamlessly and beautifully into the car including the ability to control it via the steering wheel buttons/centre-dash display).
 

wongl

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I would adjust the pin tension on the plugs first on that seat before replacing anything, free to do and quite high up the list of probable causes
Thanks for this advice - already checked the wiring and plug twice with no joy. Had to bite the bullet and ordered parts from the UK to HK despite the somewhat painful logistics.
 

wongl

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Still looking for the Workshop installation instructions if some kind soul can post here??
 

wongl

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Ok, I got the new seat mat sensor from MB dealership and fitted it to my R172. Cleared all the error codes and now I have a flashing airbag light on my dash (but no error message in the central console). Does this mean that the new sensor needs coding or calibration?
 

markjay

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Ok, I got the new seat mat sensor from MB dealership and fitted it to my R172. Cleared all the error codes and now I have a flashing airbag light on my dash (but no error message in the central console). Does this mean that the new sensor needs coding or calibration?
If you are not using STAR, possibly your OBDII scanner didn't actually erase the SRS fault codes?
 

wongl

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Ok, I managed to solve the flashing airbag light despite there being no obvious error code to clear.

Searching this issue on the internet would return several results suggesting that the SRS module has been left in an unlocked state (possibly for programming). Some literature suggests that resetting the SRS module might resolve this issue - sounds risky but it worked for me without going online to complete the programming/coding.

Now I can safely get my car to its MOT test without worrying about a flashing airbag light triggering a failure on the MOT test!
 

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