Join Date: Jul 2015
Location: New South Wales Australia
I had a similar intermittent "airbag failure" warning light manifest on a late model 2.4 with some similarities to yours, passenger airbag. Under warranty they replaced a whole chain of parts (specific airbag, controllers etc) which was finally resolved when they found a faulty connection to the ECU. Although clean, it may pay to have a really close look at the pins, connectors to the pins etc for any loose fitting.
There is also a relationship between the airbag diagnostics and seat belt pre-tensioners which can cause airbag failure warnings, under the passenger seat are the cable harnesses for these i believe
good luck, check the cabling with a fine tooth comb first (multi meter)