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Side Airbag Crash Sensor (G179) Fault Code 01221

9K views 17 replies 6 participants last post by  Tomsallis79 
#1 ·
My 2012 has been a blast but for the past 10 months or so the airbag light has been on. I finally bought VCDS from Ross-Tech and cleared the codes. They came back immediately. I googled the code, 01221 and this pops up on Ross-Tech's site: 01221 - Crash Sensor Side Airbag; Driver Side (G179) as well as:

Possible Solutions
  • Check Wiring/Connections between Airbag Control Module (J234) and Crash Sensor Side Airbag; Driver Side (G179)
  • Replace Crash Sensor Side Airbag; Driver Side (G179)
  • Replace Airbag Control Module (J234)
Okay.....
I did clean the connections as best as I could the yellow plug under the driver's seat but that didn't help. Not knowing where this sensor is located, I don't think I'm in the right area to address the problem. Car is a North American car. Where's this module and what other steps could I take to fix it?

Thanks!
 
#3 ·
Thanks for the post showing the location. I cleaned the contacts on the sensor and the plug and reinstalled everything. Unfortunately I still have the same codes. In checking the manual it states:

♦ All components (for example, cover, speaker, door trim) must be installed correctly.

♦ The door trim clips seal the system. Replace the clips, if necessary.

♦ Make sure the connectors are installed all the way in and are secure.

The door clips are there but not truly secure (thinking if I had to remove the door card I could save some frustration). The speaker grill isn't in place for the same reason.

I could chase the wires or replace the crash sensor. I'm thinking swap the two sensors and see if the problem goes to the other door or stays at the drivers thinking if its the sensor it will move with the sensor.

Advice please.
 
#4 ·
The reason that the manual states everything must be sealed up w/ all trim in place is the airbag sensor is designed to detect a rapid increase in pressure during a side impact.

The door seal isn't airtight, but it's sealed up enough to provide the resistance needed to trigger the sensor. If the door panel has a sizable opening (say you've removed a speaker for repair) there is a good chance your airbag won't deploy when needed.

Still, sealing up the door won't cause the errors you are seeing (sensor has no idea if your door clips are in place).

Swapping sensors to see if the fault follows is a reasonable troubleshooting step. Just be careful you don't inadvertently trigger an airbag deployment (you'd have to do a lot of things wrong for that to happen, but still use caution)
 
#5 ·
I appreciate the reply. I could not get me head around why the clips not being fully secure would cause the error code to reappear without the car being moved. As for safety, I fully disconnect the battery (both ground and positive) for at least an hour before doing anything. I've helped out with an accident where the airbag went off. I don't want to experience it.
 
#7 ·
I took a look at the doors through the hinges, everything feels okay.....of course with shielded wiring that really doesn't tell much. I then pulled the passenger door card and swapped the sensors with the hope that my error would now be on the passenger side. That way I'd know it was the sensor. I could pay my small fortune to Audi, swap the sensors, test everything and be done.

After reconnecting everything and performing the swap, I still have the same code.....01221 Crash Sensor and 011 Open Circuit-MIL ON. So I guess this means finding a break in the wire. Any suggestions?
 
#9 ·
I found the release and once I checked the wiring harness found my ground for the air bag broken as well as the ground for the window almost severed as well as some of the insulation on the powered line to window damaged. I plan on rewriting this discussion in the form of a how to. Next up is the Measurement block 46 project.
 
#10 ·
Did you manage to disconnect the connector in the door bellow when you looked at it?

The other end of these wires are accessible behind the footwell/sill trim piece (where the bonnet handle is). With that trim, access isn't too bad so you should be able to cut the broken wire off and solder in a new piece with enough length that the joint won't be where the wire moves/bends
 
#11 ·
At first I focused on unclipping the purple clip which is not the release for that connection. There is a small clip facing you, at least on the left side wiring harness. I was able to release the wiring harness whie pressing that clip. I removed the large speaker from the door to be able to have more access to the wiring harness. I released both the internal push plug inside the door and then removed the white nylon clip within the door that is visible from outside the door cavity. I was then able to feed the wiring harness through the door to have room to work on the wire. Once I did, I identified three damaged wires, the ground for the sensor (broken in two) the ground for the power window/lock (insulation damaged and several threads of wire broken) and power for the power window/lock (insulation damaged).

Before repairing the wire, I tried to understand why the damage. If the connection had separated due to bad workmanship the wires could simply be soldered together. That wasn't the case. That means the wires were damaged by either cut, strain, or friction. With the inner sleeve the wires run through the door sheetmetal, I don't believe they were cut. To repair the damaged wires I stripped both the wires back so I could solder away from where they were damaged and spliced a wire to bridge the gap. Solder joints are not flexible and having a solder joint in the area in which they were damaged would be a temporary fix. I insulated the joints with either liquid insulation or heat shrink tubing. I did use liquid insulation to repair the damaged insulation.
 
#12 ·
Just posting this pic for those who are unfamiliar with what's behind the door card as a visual clue to where everything is located. The red circles are where the door clips go. The yellow connector is connected to side airbag sensor. Sensor pic courtesy of eBay. You can read more on door card removal here.

@ iborg - if you can post some pictures of what you've discovered, that would be really helpful to anyone else that runs into this problem.
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#15 ·
@ iborg - For future reference, you can find this schematic in SSP380 which you can download here. It's a bit easier to follow than the Workshop Manual wiring diagram if you just need a general overview.

The SSPs (Self Study Programs) are especially helpful for quickly finding device identifiers (G179) which come up when a fault code is reported. For specific component, connector and pin locations, refer to the wiring diagram.

As always, you can find supporting technical and repair documents in the Knowledge Base.
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#16 ·
My repair worked for a year.....now the air bag light is on again. In trying to replace the harness, I can find right side harnesses but not left side in the US. Anyone know what gauge wire?
 
#17 ·
The wire gauge is given in the wiring diagrams. For more information, take a look at these two self study programs. Link here.

• SSP871003 Wiring Harness Repair
• SSP873003 How to Read Wiring Diagrams


Wiring diagrams also indicate the wire gauge used (shown in mm2), designating the cross sectional area of the wire. Wire size is defined by cross-sectional area, and is measured in circular mils (mm2). As in the example shown, “0.75 mm” refers to the area (0.75 mm2), not the diameter.
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#18 ·
Resurrecting this old thread but I have the same error code on mine. Tried clearing it down with Carista but it comes back straight away. Have visually checked the wiring through the door harness and looks ok but next step is to check the sensor itself and potentially swap with the passenger door one as iborg had suggested as a process of elimination.

Question 1 - Is it necessary to disconnect the battery while removing the sensors or just 'advisable'?
Question 2 - There are plenty of sensors on ebay for about £12 - any reason not to go for one of these vs an original Audi part?
 
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