P0106 - for 2011 BMW 335D diesel

Question

2011 BMW 335d, 50,456 miles, just out of warranty, into the dealer for pre-warranty expiration check in November 2014. Complained about trunk not releasing properly but told "All conditions normal, works fine." Began popping P0106 (lost communication with glow plug control module) last week. Scanned and reset with upscale OBD II device. Also pulled one P0034C (obscure control signal lost) in last week. Also have been receiving low battery warnings from on-board system over last 8 months (thought related to engine off but accessories on condition for brief periods). Expect that BMW installed correction to battery cable recall but haven't confirmed. Began receiving "excessive battery drain" warnings in last week along with wildly erratic electronic key effectiveness (occasionally would not open trunk, or open doors, or start car unless placed in "valet" slot--varied day-to-day). Suspected battery--measured 11.5v with "weak" on load test. Installed new battery this week (I know--"clean terminal posts first!" Violated my own cardinal rule and I now own a new Interstate 94 series battery). OE battery showed light light white corrosion on posts but hygrometer eye was green. Charging system strong. Car starts/runs fine, door locks and trunk now work fine, but popped another P0106 this morning after cold startup. Suspect a corroded contact somewhere. Any ideas?