Not 100% sure on my cause. The accessory belt idler needs replacing, it has a lot of play. The balance shaft chain idler also had a little play. Chain itself looked ok, and the timing stuff all looks fine. I'm guessing it's just a combination of the above in my case.Did you deduce the chain noise? I and another 9-5 owner both have this intermittent rattle when engine is at temp. Not looking to pull motor for new chains and guides but definitely don't want something catastrophic to happen.