Airbags, EVAP, misfires and wiper switch

QA few problems have cropped up with my 2007 VW EOS 2.0 TFSI with engine BWA – a six-speed manual box with 56,000 miles and full service history. I found the non-airbag faults after running VCDS. The faults are:

1. Airbag fault: message and warning light on dash

2. EVAP fault: no lights or message on dashboard

3. Misfire: no lights or message on dashboard

4. Steering wheel wiper switch is operating intermittently

The following fault codes appear regarding the airbag: ‘01222 - crash sensor side airbag: passenger side (g180)’, ‘008 – implausible signal - MIL on’, ‘01221 - crash sensor side airbag: driver side (g179)’ and ‘008 – implausible signal - MIL on’. The codes can be cleared, but return when the car is restarted.

I did have the same fault a couple of years back on the passenger side door only, so I removed the doorcard, found the sensor and cleaned the connections. This cleared the fault and all was fine. It would seem odd that both sensors would fail at the same time so I looked at the wiring diagram and think it might be an issue at the T28 and T28a connector terminal or J234 control unit. My plan is as follows:

1. Disconnect the battery and wait 10 minutes.

2. Remove doorcards, clean and refit G179 and G180 sensors and retest.

3. If this doesn’t work, fit a secondhand sensor to one side and retest to see if it fails again.

4. If it does fail, find the T28/T28A terminal, which is located in the left A-post, disconnect and clean terminals, refit and test. I’ve not come across T28/T28A before, so can you advise what I’m looking for – would it be two separate junctions/terminals?

5. If there is still a problem, find J234 and repeat as above. The workshop manual shows the location of J234.

6. If problem persists, with battery disconnected again and waiting for ten minutes, check for continuity between J234 and T28/T28A and the sensor.

7. If all this fails, find the earth point, clean it and retest. Which earth point would I need to check for the T28 terminal and J234 control unit?

8. As a last resort, send J234 off for repair. Any thoughts on this approach?

Regarding the EVAP fault and misfire, I think these might be related. There is apparently a common problem that happens after brimming the tank. I have cleared the faults and they did not return, but have not taken the car for a run due to the airbag problems. 1. I have run the output test on the N80 valve and it seems OK. There were no problems reported and it switched on and off via VCDS.

2. Next, I plan to inspect the pipework for leaks.

3. If nothing is found, replace the valve. Any thoughts about this methodology?

For the final fault, I plan to test it by setting the wiper switch to intermittent and running a hose over it to see if it works.

Could any of these faults be related?

The reason I say this is that, over the years, the roof has leaked on both the passenger and driver’s side, but it has been fixed and the car is dry. Could this have caused some issues which are only now coming to light?

As a follow on from this, I found the following warning in my EMO service manual:

▶ General safety regulations concerning work on airbag, belt tensioner and battery disconnection units (pyrotechnic components).

▶ When working on the airbag system (pyrotechnic components and the airbag control unit -J234-, wiring) disconnect the battery ground cable while the ignition is on.

This would seem an odd approach to me, I’m sure there is a reason but not sure what. If the above is true I would change my approach as follows:

Airbag fault – continuity testing...

1. Switch ignition ON, engine OFF

2. Switch any electrical items OFF that

I can radio, auto lights, etc., and then disconnect battery earth lead only.

3. Disconnect crash sensor plugs/ connectors, T28 and T28a plugs/ connectors and J234 plugs/connectors and airbag plugs/connectors under driver and passenger seat so they are all disconnected.

3a. What about passenger and driver airbag, would I need to disconnect these as well, if so how do I do this? 4. Undertake continuity testing on wiring for cash sensor only.

5. Once complete, reconnect all connectors. 6. Not sure if the ignition switch would still need to be on when I reconnect the battery earth?

I would be interested to know what your advice would be regarding leaving the ignition on when the battery is disconnected and when it is reconnected. Seems an odd way to do it, possibly increasing the risk of damage to electrical components.

Rob Slater

AThe information I have on the ‘01222’ fault code for the airbag is ‘No or Incorrect Basic Setting/ Adaptation – Wiring/connections between Airbag Control Module (J234) and Crash Sensor Side Airbag; Passenger Side (G180) faulty or Crash Sensor Side Airbag; Passenger Side (G180) faulty/ Airbag Control Module (J234) faulty.’ The information for code ‘01121’ is ‘Wiring/ Connections between Airbag Control Module (J234) and Crash Sensor Side Airbag; Driver Side (G179) faulty. Crash Sensor Side Airbag; Driver Side (G179) faulty. Airbag Control Module (J234) faulty.’

As you have said it is unlikely – albeit